Hey Denny, welcome to CHR! Glad you're here, and that you're posting. I can't answer for the '37 to '40's, but for me it's always good to keep some continuity, which here would be Ford in Ford. I can't tell you how many times I've had positive comments on my '33 regarding the choice of running a Ford engine. The guys who've been around appreciate that allegiance. I'd give you a very strong vote to keep the Ford driveline in the '38, and I look forward to some pictures when you have time.