Flatout_friesen

So I bought a 1981 Datsun 280zx with a stock N/a l28e engine in it...OR so i thought. We tore this thing apart and found that it had an F54 block with an N42 head, BUT, with dished pistons. So I'm not sure if these are early n/a dished pistons or just a turbo block that has been changed to run n/a. Anyway, the original plan for this car was a low boost turbocharger upgrade. so i bought a P79 head for it, dropping the compression ratio to 7.8:1, compared to the factory 8.7:1 with the flat top pistons. I started a new thread because i haven't seen one thread that i can relate to with this Mix-n-Match motor that i have. My questions are: 1. Why do you think this block has been pieced together from many different years of Zs and using dished pistons for an N/A build? 2. how much boost would be safe to run with that compression ratio (7.8:1) provided my AFR is in a relatively stoich range? I have a wide-band for it so i can monitor the mixture and will have an intercooler, bigger injectors, etc. Thanks to those who take time to reply.