The compression height is too large, but no problem to cut them down to fit (1.80 SBC Vs. 1.70 Poncho 350). The valve reliefs will be wrong, but no problem to add the right ones. The pin diameter is .927, so you'll have to bush your Pontiac rods to use them.

In almost every way you are going to be out about the same amount of money. My plan was to use the Olds poistons and "soft head" the tops with corner reliefs for the valves. For most rebulds, a set of purpose-made pistons would make the most sense.