The weight difference is probably negligible and doesn't effect performance. There's an article in last and this month's American Iron about Hillside's (site sponsor) 98" build and they put in S&S adjustables even though the entire top end was apart. Adjustables are the "perfect fit" although I didn't use them in mine.

 

Just did mine, not hard at all. Get the factory manual, read and read some more until you can do the whole job in your head. Then you will have all the confidence you will need. Once I understood what I had to do, I used the manual for tq specs. You will need a special puller to remove the cam bearings, and I suggest you use the up graded cam bearings. If you reuse the OEM push rods you have to remove the tank, I cut mine off and replace with S/E adj push rods, I my little brain a lot easier. PM me if you need any info will be glad to help.