Well after some cleaning off of the intake manifold I finally found the
GM letters stamped on it and also found it stamped on the back of the
engine block. I bought a brass freeze plug today and installed it onto
the engine and finally got the engine running, had to also adjust the
points...

What is a good way to flush out the engine block as far as the cooling
system goes?

Thanks for your input its much appriciated...

Radman