Exhaust, where do I cut?...

[Jpwhit1]

... And will this combo work?

 

[fredintoon]

... And will this combo work?

Hi Jpw,
sure, that'll work.
But it's a lot of work to do it right and if you are just doing it for looks then I wouldn't think it was worth the hassle.
But if the original mufflers are rusted out "a man's gotta do what a man's gotta do."
OK then, first you have to cut through the muffler cones twice and split between the cuts to peel the thing like a banana and see the complicated hookup inside there.
Your object is to cut the muffler off in a way that exposes enough of the header's inner pipe to put the slip-on muffler on.
The rest is a matter of arranging pipe clamps and matching the diameters.

 

[tonyc]

Search the archives there is an excellent article on this procedure.

 

[650Skull]

Comprehensive tutorial on the procedure by pamcopete
http://650rider.com/index.php?name=Forums&file=viewtopic&t=7611

 

[Jpwhit1]

Yes, originals are toast. I bought these mufflers before I had the 78.