Take the freeze plugs out yourself and clean it. I did that before I took it to the machine shop.

You'll need some picks/screwdrivers/hard wire, bottle brushs, and an air gun (long nosed would be nice)

I have no cooling issue with my new motor. And I don't even have a fan shroud on it yet. Ran it at 6,000 rpm for about 50 laps throughout day with 150 miles on the new motor.

Did the same thing in 1994 with the 340 motor before this and never had cooling problems driving across the desert in the summer at 3500+ rpm all day.