honestly i would stay with the early 289 head and maybe pui tn a set of chevy valves, the reason being that the early style 289 heads do not have the thermactor bump in the exhaust and thus flow way better in teh exhaust. also the exhaust ports are oval in the new head, and rectangular in the old heads..
a better idea is to get a used 302 crank and install it with 302 pistons and your own 289 rods that are slightly longer. thus instaling the pistons almost at zero deck height, yielding better quench and horsepower.
you might want to check out back issues of Hotrod magazine, they did a 400 Hp 302 for arround 1500$ with that combo. i think Joe Sherman did the build up.
cam was a 280 isky mega cam.
good luck with it
ps. the 400-600 or so dollars youd have in buying the late model heads are much much better spent porting the 289´s
If you have the heads already, use them. If you don't, go get a set of the explorer heads. Use the valve gear for the Explorer including pushrods. These are the equivelant of the "Cobra" head. Alittle more cam wouldn't hurt along with a new timing chain, Now's the time.
You do not want to use the late model heads. They are much more restrictive than the 289 heads. Instead, port and polish the 289's and put in some chevy 2.02's. Also, get yourself a 302 crank and pistons. You will get a longer stroke out of the 289 rods, and therefore, get more horsepower without giving in to streetability. You will need to chang your cam as well, but I am not sure on which one will be sufficient. A shotin th dark would be a 275. You should be able to find out from any engine machine shop. Just make a few phone calls, an do a little research. Goodluck!!!!
For the best operation and minimum valve float use the Crower or Manley cut -to-fit adjustable p.rods. Measure each rocker to lifter length and make sure the p.rods compress the lifters for 1/4 to 1/3 travel.
hi. i did that very thing. 5- bolt 289 with polished and ported 302 heads, ( 1968 i think). i used com cams dual pattern 275, with their pushrods for 302, set the valve tension with the shims they provide, and keith black pistons, turning 246 hp at the rear wheels. eldelbrock 600 carb on performer II manifold, msd ign. i also have a set of H P heads for sale. good luck. joe
Does the late model 302 have a roller cam? If it does, that means the lifters are taller than regular lifters, so the pushrods are shorter. If it doesn't (before 85) then use those pushrods. The heads you are talking about are probably pedestal mount which i think they started using in 1979. So i could be wrong, but the only pushrods that would work in your case would be the pushrods that came on an engine with a flat tappet cam and pedestal mount heads. (your same combination after installing 302 heads on the 289) You could get these pushrods from a doner engine or summit.