If you do decide to use the welting, the Model A cowl welting is smaller than the typical fender welt. The problem with the welting is that it goes from the bottom of the cowl, over the gas tank and down to the other side of the cowl. The cowl is riveted in the lower corners stoping the welting from going between the cowl and the body.
I used the welting from Snyder’s as well. edit: I painted my cowl off the car and installed before painting the rest, so no paint on my welting (not the reason I did that, but the result). Not sure if that’s important to you. John
On the Model A's that get real paint, I've used 3M body seam sealer that can be painted over. That way there are no water leaks. The 1 old paint car I've done had original still in it that I left.
There are several manufacturers, step up and buy the BEST, it saves a lot of aggravation. The guys on Ford Barn will know the supplier. Bob