What size bearings should I go with?

 It's best practice before buying any set of bearings to first measure your bearing journals with a set of quality micrometers. This is usually handled by your machinist/engine assembler. For your convenience we've provided some factory specifications:

RB26 Main Bearing Journals Inside Diameter

⦶ 58.645 ~ 58.670

RB26 Main Bearing Journals Crankshaft Diameter

⦶ 54.951 ~ 54.975

RB26 Connecting Rod Big End Inside Diameter

⦶ 51.000 ~ 51.013

RB26 Connecting Rod Big End Crankshaft Diameter

⦶ 47.961 ~ 47.974