If it's close to stock, it'a a bypass and you can plug the lines. An easy way to check it to plug them with standard brass plumbing fittings, then spin the oil pump with an
electric drill. You should flow oil everywhere, easily. Good way to check oiling in general, IMHO.
It's *possible* but unlikely that the block was modded for full-flow, in which case you should not plug them.
As noted, rubber oil line from autoparts or mailorder will work, so just go ahead and replace'em....
G
