alluminum heads

[6T9PONY]

By the way, the "1.90" numbers is the size of the valves in the heads. They were probably 1.90/1.60 or something similar to that. That's the size of the intake and exhaust valves. And no, they have absolutely nothing to do with boring out your engine. And you cannot "bore" a 289 up to a 302. You could add a different crank and get that many cubes, but not by boring.

Boring means increasing the diameter of your cylinders in your engine block. By doing this, you gain cubic inches. But with the normal .030 overbore you don't gain anywhere hear the 13 cubic inches between a 289 and a 302. If you bore a 302 .030 over, it comes out to about 306 cubic inches. A 351 with a .030 overbore comes out to about 357 cubes.

Boring and stroking have nothing to do with your cylinder heads. You cannot gain cubic inches by adding better/different cylinder heads.