I've searched on the internets (with no luck) to find out if I need a specific sized head gasket for my rebuilt D15b.

my question is: since my engine is rebuilt, do I need a head gasket that matches the cylinder bore? Does it matter? logically it seems that it would..

I've never tore apart an engine this much, so I want to make sure I dont F it up.

Oreilly's has 2 gaskets ready for me, size 2.990 and 2.998 and i have no idea what to get.

Do I need to take off the head and measure the old gasket?

about to sell my car but I want to get as much as I can out of it, and I don't mind replacing a head gasket...