The primary difference between the "POLY" series engines and the later born "LA" engines is in the block, heads and intake. Also take note of the valve train layout needing a different cam. Beware, a "LA" cam can slip right in and be bolted down to the timing chain.
On the blocks deck surface, there is a water way at the drivers rear and passenger front between the further most cylinders. This water way will not let you bolt an "LA" head to the block and work.
Otherwise, the heads can and will bolt on. OH, there's some differences in the holes drilled into the head, or cast into the head, but if one was to go nuts with a welder and close up the holes, there big by the way, you could run a "LA" head on a POLY.
Dimensions? There extremely close. The blocks are other wise the same. It is easy to I.D. a poly block due to the lack of freeze out plugs on the front face of the block. The motor mounts are the same, so a drop in to any SB K-frame is a drop in.
Headers are a serious problem for A body cars at this moment. There are none. Exhaust manifolds must be used and they are a serious bottle neck for performance applications. Custom header flanges might be obtained from TTI or custom made with a big help from exhaust gaskets. IF you go to a machinist to have him make some up, make the flange 3/8 thick. What the heck right!?!?!
Otherwise, from the outside, the timing chain cover is slightly different with an extra bolt hole. You may have noticed this in the gaskets you get for the cover. Timing marks are also on the other side of the cover like some older "LA" engine.
Otherwise, performance parts are easy to get since it can use a lot of "LA" parts. Crank, rods, bearings, gaskets except intake and exhaust, balance's, flywheel/flex plates, springs rotor oil pump and pick up, oil pan, etc.......
The hardest part of dong a POLY engine up for some respectable power would be;
Intake manifold
Heads, they do not flow so well and will need a good hand on them.
Pistons and valves can be custom made. IDK if there are valves sitting on a shelf, but slugs are custom made due to there valve arrangement.
Here, is where you see why these engines are also called a "SEMI HEMI"
Gary Pavlovich did the engine build in the MoPar Muscle (As mentioned above)
His stroker Poly @ 402 cubes )IIRC) was a mild manor ed (cammed) engine that just simply pounded out some nice numbers for it's build.
We were just sharing a few E-mails back and forth about the price of the Poly intakes. The cheapest one I have come across was for $525 + shipping. He said to me, "Yep! that's about right!"
OMG, I am falling over. SO, I'm questioning my POLY build! Between that price and custom stroker pistons...eeeekkkkkk!!!!!!!!!
One last word about a POLY, the back side of the cranks can be tricky. Sometimes there 6 bolt, sometimes there 8 bolt. Sometimes you can not hook them up to a newer trans due to the flange's dimensions. It just doesn't fit.
(IMO, sell it, roll the money over into a "LA engine" You'll be ahead of the game.
