Old Art Carr valve body

The trans in my mud truck has an old Art Carr Manuel valve body with trans brake .This is not a mud race truck but an open pit Michigan/Florida style bog truck. It goes in the pit and ran hard through all gearsup and downfor 20 minutes at a time or till it gets buried. 850hp bbf. Trans brake isn’t used. This trans has always had a slight delay when shifting and a flare. Here recently it just slips in second gear under power and gets hot quick. So I’m looking to take it to the trans shop for a rebuild. Should I get a new different valve body or is it possible to set up the old Art Carr valve body to work decent?

Here's the fix

TCI trans brake fix pre frank!
If it's a TCI I have a fix for it as the problem is the 2 checkball slots in the lower half of the valvebody are too large and too long and the checkball cannot find there seats in the spacer plate. there should be 2- 1/4" steel checkball ,one in each slot . you need to fill these slots with JB WEld or another good 2 part epoxy , then using the spacer plate as a pattern mark the 4 checkball seats in the epoxy - using a 9/32" drill bit drill 4 holes in the epoxy approximately 9/32" deep at the 4 marked spots, then using the drillbit router a new checkball slot in the epoxy , make sure the checkballs will roll free from one end to the other in both slots - install the spacerplate and check to make sure the checkballs will roll from one end of the slot to the other and not over shoot there intended seat, the holes in the spacerplate should be 7/32" for the High checkball and 5/32" for the low checkball . In between the lower half of the valvebody and the spacerplate there should be a gasket ,if there is not make one out of .005" gasket material, Torque all Valvebody bolts to 55 inch/lb's
Frank