Vortec coolant bypass?? Any info

[Tommywalton]

I have a vortec long block replacing a one piece rear main 350. I think i may have an issue. Im using all my other parts sans old long block. The vortec has no coolant bypass and my old engine does. Ive searched this forum and only found confusing conflicting info. Ive read on sbc forums this is not an issue if you use a heater core which im not.

Does anyone know if i have to plumb a bypass and if so exactly how. Thank you