340 Pistons

I know I have the info baried some where. My '73 340 is a low comression mess. I was "busy" @ work looking up parts for it... Will '68 pistons fit ( I know the bore's the same before I get any "fun" answers) The only thing I'm concered with is the pin and internal VS external balance.... I'm not sure what I have to worry about. The only reason I'm even considering changing the pistons is to up the compression ratio. I would rather not do any machine work since it @ a clean std bore and I don't like the idea of milling the deck or heads if I don't need to.
Any one want to swap up or down for my pistons to the high compression ( New ) pistons? This is a back burner project but I would consider buying the pistons or maybe a swap W/ or W/O cash for what I want.