I ended up getting used seals from a truck that was being parted out. I have not heard of any aftermarket replacements but you might be able to get a similar profile seal that will work from one of the restoration places.
Steele have a good reputation but none of the "street rod" profiles on their site look close but they may have something they can match up if you cut a section off one of your seals and send it to them. Also check
ATS - there are a couple of profiles pictured that look close.
The tricky part is that there are 90 degree corners on some of the seals where the rubber/plastic is welded to make the corner. Very hard to reproduce at home. You might get by with cuting a seal and using RTV or 3M weatherstrip adhesive to seal the corners, I dunno.
And if your seals are not too far gone you might consider patching them. I've had luck inserting a length of cylindrical weatherstripping foam (see Home Depot, et. al.) into the stock seals and carefully covering the patch with black RTV. With black RTV the patch is not too obvious and in my experience it does seal OK. If you go this route clean everything real well so the RTV will stick and plan on not closing the doors overnight while it cures.