I think your answer is likely to depend upon how classic vintage you want to go with the old classic pre 64 vintage Model 70? I had a similar issue when I set up my old classic FN Browning Hi-Power 308 for an African PG hunt. That rifle was built in 1963. I wanted a variable that went down to 2 or 3x on the low end and no more than 12x on the upper end. It was going to be set up to shoot out to 300y but in reality the longest shot I took was 202y. I like illuminated reticles for all conditions utility but since my 2nd rifle had a nice illuminated Swaro on it I was not handicapped by going vintage.
In the end, I chose a vintage B&L Balvar in 2.4-8x which is a FFP optic. These are obsolete and tedious to zero but once set up, they make a near bulletproof package. I used a vintage Kuharsky detachable mount. These scopes do not have turrets and are zeroed by adjustments built into the base mounted on the rifle. It allows the optic to be moved from rifle to rifle and yet retains zero on each rifle via the adjustable base mount. While old and clunky, these old Bausch and Lomb scopes possessed superior glass to near anything on the market in its day. B&L had access to a deposit of nearly pure quartz sand in the Pittsburgh area. This produced lenses of near perfect optical clarity. They used this glass to build the spy cameras used on first the U2 and later the SR71 spy planes. Occasionally one of those big ass lenses would be found with an occlusion and could not be used for its intended purpose. So, they would cut up the lenses and build rifle scopes from it. The old Balvars have clarity that rivals even the best tier 1 optics today and are able to do this without the use of fragile ARC coatings. You can dial them from lowest to highest magnification without the need for parallax adjustment. The tapered reticle is easy to see at low power and precise at high power. It is telling that my rifles were dropped by baggage handlers at the airline and my other rifle's scope had to be adjusted before use in Africa being 6" high at first shot. The old vintage Balvar was dead on from the first shot despite it being shipped in the same case.
I was even able to use this optic while night hunting in Limpopo for some of the smaller nocturnal critters and could easily pick up the reticle in such low light conditions. It has limitations since you cannot adjust the POI easily in the field so, shooting very long ranges where hold over or dialing is required is not an option. But, since my max range was 300y, I just zeroed it at 200y with my 180g ammo and that made it 2" high at 100y and 3-4" low at 300y. It worked perfect and I took five animals with it and all of them were one shot kills. To be sure, you can do better but this little gem cost me only $60 on Ebay. Compared to a top tier Leupold or Swarovski, etc and it was quite the bargain. I have two Swarovskis and one Kahles hunting scope as well as two Leupolds a Zeiss and a number of Arken scopes. All of these have very good glass. The clunk little Balvar is on par with all of them except possibly the Kahles which is amazing. I do not own a Razor or a NF ATAC-R but have had the opportunity to play with both and while they are very good optics they too are only as good. My Leupolds are not top tier products from that fine mfg. They are older VX2 and a newer bottom of the line 1.5-4x. OK to be sure but not as good as the others. Leupold does my some which are much better than mine.
In 1963 I could have bought three of the Medallion Grade FN's for the price of a new Balvar. It is a unicorn. Now, I am going to be in Free State next year for some hunting and my PH advises that I need to be able to shoot out to 400y in some cases. I could have swapped scopes on the FN but, I like it as it is so well that I bought another rifle and put a proper FFP adjustable optic on it with lighted reticle for that trip. Pic of the little FN below for your viewing.
Something to consider before you decide. The rifle does not know what sighting system you use to point it downrange. It will shoot just as good with iron sights, a fixed power 4x or a top tier 3-18x optic. The only difference will be your ability to see well enough to aim it precisely. All that is needed is enough scope to see well in practical conditions to hunt. A wide field of view is desirable. A low power of 2-3x is good. Lower might be better if you are hunting in dense cover where closer shots are the norm. Most of my shots were at the lowest power setting with only one exception. What works well at the range is not necessarily the hot ticket in the field. What and where you are hunting will drive much of the decision making.
