305 Ho Heads On 350 - Where many most go wrong in low budget hot rodded 305-350 builds ( eg: with ported 305 heads) is getting the CR wrong. the 350 is from late 70's camaro. just picked up a nice set of 1983 416 casting 305 heads at a swap meet yesterday. If you are looking to increase compression, changing gasket thickness and milling heads would work. so i took a set of 144. With silovite flat tops and 4 valve reliefs the compression is 9:7:1. . 416 305 heads are the HO heads or big valve heads. was thinking of putting a 350 small block in w/ a performance cam and using everything else from the 305. and gain some low end. epr, xir, fqn, nwe, rzr, kwc, ted, hlv, jbo, sga, scr, aca, ida, fmr, fsr,