This winter i will be putting a heads/cam prepped lt1 in the car with a stock 4l60e. Over the year i plan to build a 383 and some form of power adder.

My question is for mainly a cruise, strip car should i just leave the 4l60e stock and invest the money into a nice th350 with brake or build the 4l60e. I know the car will be making weekend road trips of a few hundred miles distance if i can't trailer it. How would highway use suffer from the th350? Would i still be able to cruise at like 75mph and say around 3k rpm or under?

Thanks for the help!