I have an Ishapore we came across. Nice rifle, I suspect it will shoot fine. My understanding is the Indians made it in 308 (7.62 NATO actually), because they had the machinery to make the rifle, and they weren't getting enough FALs fast enough. So the bolt guns were made and given to reserve troops, with the FALs given to the main forces.
It's chambered like that in the factory, not a conversion; and I haven't heard of any failures (as compared to some of the Mausers that WERE rechambered, where there have been).
I'm not going to get into the 308 vs 7.62 NATO discussion too deep, other than to say I only shoot NATO or light 150 gr 308 FMJ through mine. I have contacted Armscor in an email, asking about it, and they stated that in THEIR new manufactured rds, the 2 are identical/interchangeable.
Other than that, I shoot Magtech NATO marked ammo.
I also have a C308 (Cetme), that I shoot any/all 308 or NATO in, including steel. I don't put any of the steel in the Ishapore.
As an aside, we got the Ishapore before the ammo crunch. My son tried his hand at a Mad Minute and did ok, with a big grin. I'm a lefty, that didn't work out so well for me.