I don' have a thermostat. I had coolant coming out of the exhaust so im fairly confident that it has plenty in it. The imco exhaust I have has no provisions to drain it. Otherwise I would have done like you said and drained the block and called it good.

How much HP does your current motor have?

I have not put it on a dyno but i would say by the parts that are in it. Should be 600 all day. Maybe a little more but have no way to know with it in there.

Crying shame I had to wait until May to get it out. But we had a long hard to predict winter. Finally got it out from under the shed today. Drug it to the DMV to register it. Come home and pulled the pollen covered cover back to get to the controls and access the engine. Checked fluids. Put the outdrive in the bucket. Filled it with water and give her a whirl. It fired up and ran well. I dont have my vacuum gauge at home but I adjusted idle mixture by my nose. I'll get the gauge on it Sunday. The last few runs last year idle was a little rich. Got a bit of cleaning ahead of me on the upholstery. I'm disappointed in 3m 303. I put it on 5 layers thick before I covered it. Still got some black spots.
https://cimg7.ibsrv.net/gimg/www.off...59f8ede0d7.jpg
https://cimg1.ibsrv.net/gimg/www.off...bcfd2cb135.jpg
https://cimg7.ibsrv.net/gimg/www.off...d26f523895.jpg
https://cimg4.ibsrv.net/gimg/www.off...117a902236.jpg
https://cimg3.ibsrv.net/gimg/www.off...d37cf4498d.jpg

Lasr 2 pictures are before and after using 1 application of the cleaner with a towel. Gonna hit it with a soft bristle brush and get it as good as I can.

Ran it Sunday after checking everything and giving it a good cleaning. Got a little heavy on the beer and on the way home I stuck it for about 45 seconds. At 5900 rpm she was running 71mph with a little over a half tank and all my junk in it. I was grinning like a mule eating briars.:boat:

What cam have you got in there Hunter? 5900 is singing!

https://cimg3.ibsrv.net/gimg/www.off...5d84a6925e.jpg
More than I'd like to twist but I wanted to try it. I'm thinking a 24 bravo or 25 revo would be good on it. The 22 planes so quickly though.
cam card

Tom, this is from cranes website. I'm only at 10.5 compression and 509ci though
https://cimg1.ibsrv.net/gimg/www.off...784ecccce2.jpg

https://i.imgur.com/bBcEpQz.jpg