I'm 6' and between 195 and 220 lb depending on the year.
I've driven hundreds of miles in a day and thousands of miles in a week in my 52 with worn out stock seat. I fit just fine, and only after the first 4-5,000 miles did the seat start to feel a little stiff.
More recently in the 51 I've put at most 100 miles at a stretch so far, I still fit just the same, the stock seat is still comfy enough.

I expect after you get it running and take it for a drive you'll figure it out. You're smaller than about everyone who has commented so far and we don't have trouble fitting.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-