Help identify racing engine?

Does anybody know who "JM" might have been? I think I've got his engine (or at least one he machined).

I've been collecting KZ stuff since about 1988. Somewhere along the line I acquired a set of modified engine cases. I'm getting to ready to build up a stock KZ900 and I figured this would be a good time to figure out if there's an interesting backstory to this engine or not. The serial number is Z1E 30881 with the raised rim around the number. It also has the raised rim "Kick Starter" in the casting. Based on those three things it seems to have started life as a 1974 Z1A, although there's no evidence of any black paint. It was bought in Ohio sometime between 1987 and 1992.

The piston sleeve bores in the top case have been machined out to 81.3mm (3.200"). I'm pretty sure when I got it it had stock KZ1000 cylinder and pistons, but obviously this was modified. It had stock studs, used stock crankcase bolts, didn't have a stiffened crankshaft cap, the crankshaft was not welded, the oil pan was unmodified. So really the only thing unique is the sleeve bore mod. There was a weld repair inside, but no evidence that a transmission had exploded or anything that dramatic.

There's a hand stamp on the lower half "JM 879 1130". As near as I can tell (based on thumbing thru my vintages racing parts catalogs from Wiseco, APE, Racer's Supply, Fast by Gast, etc.) nobody ever made an 1130 kit, although Wiseco came close with an 1135 street kit. The KA629 sleeve had a 3.200" OD and was used with the 1105, 1135 and 1200 Wiseco kits, so I think it's likely it used one of those.

So - mostly curious if anybody knows what shop this engine was modified by.

Turns out I do have the pistons and block after all, and they are clearly for a turbo application. I’ll probably wind up selling the whole lot since I’m not really interested in taking on a turbo build.

That serial number corresponds to 1974 Z1A. Only the Z1 version came stock with a black case, but many '74's and '75's were painted afterwards.