350 jug on 250?

[holeinthehead]

Hi All
I'm sure this has been covered, but searching hasn't been fruitful.

I bought what I thought was a 74mm replacement piston/cylinder for my 250 Monza on eBay, and (shocker) it's not as advertised. The setup is 76mm - which I understand is the size of a narrowcase 350 (right?).

I also have a 350 widecase that needs similar love, but I'm pretty sure a NC cylinder won't work on a WC.

Questions are:
1. Am I right re. NC/WC? i.e. The 350 Sebring jug won't work for my widecase, correct?

2. Is there any thing keeping me from using the 76mm setup on my 250 monza? The cylinder fits, but I don't know if there are tolerances re. power that I'm taking for granted - the connecting arm says 250, for example.

Thanks in advance.

[holeinthehead]

NOTHING?
Guess I'll just give it a shot.