My Dart Swinger Project!

Budgets make it tough..... darn. Yep, no way on that cylinder.

Option: You could bore that one cylinder... not unknown at all. At a .030" oversize, it is a whopping 0.6 cubic inches larger out of 40 ci... a whopping 1.5% difference. You will get more variation than that from different ring sealing and different cylinder filling.

For balance, just drill a bit of weight out of the new oversized piston's pin bosses and make the total of the piston+pin+rod weigh the same as the average of the other piston+pin+rod assemblies. For a budget situation and limited to mid RPM's, it will work OK. (It'll probably end up being the best cylinder in the engine LOL)

The trick is measure the compression height of the existing pistons and match that up, so that the 1 cylinder will not be at a different SCR.

However, I'd take it to a shop and ask their opinion on the rest of the bores before doing this. Or, borrow a bore gauge and check them out.