larger 1256 valves & oversized valves

[Icedmunkie]

Does anybody know where i can get larger valves and oversized pistons for a 1256?
Also after a bottom and top end gasket set for the same engine.

[pbottomley]

what do you need larger valve sand pistons for?

[Icedmunkie]

1256 hc engine
Also are the heads the same across the board for 1256's ? just got one engine with single downpipe on exhaust manifold and one with a twin downpipe.