Assuming 1st gen motors have the same head clamping force as the p pump 12v's (I can't imagine why they wouldn't), 40 would be the earliest I'd start worrying about studs or fire rings. I have stock unretorqued bolts and gasket on mine, and I run 45-50 quite often. I've previously sprayed it with nitrous while running these boost levels, and my timing is up around 19. I may just be the luckiest guy on Earth, I dunno.
Remember that studs aren't the only option, there are upgraded bolts available for much less. They also clamp less than studs, but more than stock bolts. Might be a good compromise, especially if you're not trying to go much past 50 psi.