I spent many hours with the primary clutch spring/weight selection on the Interceptor. I am using a comet on #593. Also, ported cylinders to match the Aaen pipes. I had the head machined (squish band .85 mm) and chamber deepened (running aprox. 155 psi hot). If you checked the stock "squish band" tolerance with the copper o-rings you'd be amazed at the clearance (wide). I am using a set of new 530 kawi jet ski pistons (modified wrist pins). The pipes are advertised to make power in the 9000 rpm range so I've clutched accordingly (too bad I don't have a dyno to confirm). If anyone is interested in the comet weight/spring setup I could check my notes-would gladly share any info if it helps. I was able to keep engagement at 5000 rpm's for trail riding. Aside from arguments I've heard over the Aaen pipe power increases, one thing is for sure... you "feel" the weight reduction in the front end (handles better). We are talking at least 20 lbs weight savings. Also using 38 mm mikunis. I had to play with the jets/needles quite a bit. There were some great posts on this site w/carb calibrations (thanx to all). Stock gearing... changed front leaf spring pin location. THIS IS A FUN SLED!
As for the 80' LTD 4/6 (all stock)... once you get the cadillac moving say, 20 mph or so, sled pulls hard. If I were a betting man I'd quess the LTD would give the Interceptor a good run (on top end). I don't think stock for stock, the horsepower ratings are much different... 75 vs. 85hp ish.