Actually the "on the Cheap" was to reuse your 400 pistons (Longer CH 440's won't work) and bore your 440 block to 4.342" (.022 over) and then (IIRC) use the 4.15 crank and the 440 LY rod and you get ~491 cubes.

You might need to check my math but I think that's right...at least it's feasible.

It'll be heavy and I think the slug still winds up down in the hole but the bottom end will lighter than a stock 440 and it'll be cheap (the cost of the crank and balancing).

I mocked one up that way with spare parts but I never built it...you'll be limited on cam lift due to no eyebrows inthe slug but if you want a low buck torque motor I'll bet a MP 528 solid would clear.

But I could see a very low buck "junkyard" torque motor turning high 11's or lower pretty easy.