451 overheating, even when moving

I brought my 71 Duster home yday, and had to stop 2x to let it cool down and puke :( what is normally a 30 min drive, using the highway, took almost 3 hours while avoiding the highway

it has a 400 bored out to 451, and would get up to 230f after to 12 minutes, and it wasn't even 30c (less than 90f?)

It was a drag car and the engine is very high compression which contributes to the problem

3 core champion rad, electric fans that are always on when running, using a manual switch

Everything was flushed so there is a possibility they put too much back in the rad, what's a good level? Touching the top hose? Above the top hose?

Any suggestions to help it keep cooler are appreciated

I don't know if they replaced the t-stat, so I've ordered a high flow Mr gasket, the milodon is sold out everywhere I looked

I'm going to grab some water wetter this morning, it can't hurt, and the car is no longer drag racing anyway.

My neighbour, a retired mechanical engineer who used build race engines as a hobby, has suggested adding a big remote oil cooler to the mix with a t-stat controller.

Thanks
Make sure its purged, make sure the timing is right, make sure the radiator cap is good and after all that pressure test system see if you got a head gasket leak... it from there you'll focus on the tune or more radiator capacity