Jeff,

From some stories I heard, some of the original pre-production crate engines may have been built with OEM pistons, flattops or dished. But once production began both versions had higher compression flattops with notches.

I see what you're saying in the '93 and '94 catalogs. But the .474" cam would seem a little stout for an 8.0-1 compression. I have some more articles around but don't have time to do more digging. However, the IHRA specs for my 300hp version, which came from Mopar before they accepted the combo, calls for flattops with notches.

I just found that the 1998 catalog, page 25, lists KB flattops as "Service Pistons for the MP 360 Commando Crate Motors, 9.0:1." It doesn't differentiate between the 300hp or 360hp versions. Perhaps they were early KB 107's. The notches are not like the 2 "eyebrow" current versions, but they would likely provide about 9.0:1 if the heads and/or block were not milled a lot, just cleaned up.

P5249478 - 4.020"
P5249470 - 4.030"

I've been told that both versions of the original Magnum crates had OEM shortblocks.