The long cylindrical muffler on our single exhaust Warlock is rotted out and most of the options are short performance orientated units. Anyone here of a good replacement muffler that might not require too much welding to fit up?

If you go to a good NAPA store I bet you can find one. I made a similar replacement on a brand F PU and that worked for me.

The experienced parts guy found an exact 7" OE replacement (~$110) and a generic 8" round (~$70). I had room and went with the generic. Maybe gained a pony or two and sounded better.

The one on my 68 is a stock 72 and up unit from a parts store and is nice and quiet.

Dynomax makes a super turbo (round) for RV/motorhome/HD applications but a stock type replacement would be a lot cheaper.

When I did the exhaust on my Jensen Interceptor I had two poor shape large cylindrical mufflers. I looked in the Walker catalog and matched the dimensions exactly. Worked perfect. Walker has a lot of different cylindrical mufflers.