will 305 heads fit on a 283 motor?

Yes. With the 58cc chambers, you'll even
get a bit more compression. Another good thing
is that you will have bosses for accessories
if you need them.

Try to get the 416's, as they flow better than
many other SB heads.

The 305HO, -601 heads have chambers more like mini-double-humpers so they are slightly better then the -416's that are more squared-off, imho..

My measured -601's have about 55 cc chambers and 160+ intake ports and are going on my 283 motor onna these days for the fun of it.. I was pleasantly supprised b/c I was expecting 156/158 cc's and 58/59 cc's...

Good value for the buck on a low compression motor that can use them, imho..

pdq67

Perfect Fit from What I've been told....I just purchased a set of 58cc, 1.94/1.50, .510 lift Heads from a place called AM Perfromance in Houston. Looks like its going to be a good deal. The heads were real cheap too, $375 for a set ready to bolt on - minus pushrods and rockers.