I'm guessing you bought this on eBay lol.
There's a LOT of 70mm out there, I wasn't too pleased with the Tri-x nor the Pan-X I got from the 60's but the GAF seems amazing lol. I haven't tried the.
The Tri-X was SUPER foggy, so good luck, I suggest fixing it for a few extra minutes than normal. It will curl a lot so scanning or printing will be more difficult. Have you found a 70mm spool? They aren't easy to come by.
I've learned a lot from all the 70mm I've shot, I love the stuff it's a pain but somehow satisfying.
I would suggest developers that are really fast like I used ilfsol 3 because of the 4 minute dev times it cuts down on fog it seems any really short dev time developer is recommended for older films.
That's my 2 cents
Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk