clutch and rear end questions

[Mr.Matt]

after switching to royal purple my rear main seal has decided to commite suicide
so it needs to be replaced, fun fun

so i figured that if i am paying someone to go in there i might as well choke on the cost for a new clutch and flywheel.

I have a centerforce dual friction in there now with a refinished flywheel and about 120000 km on it. I cant say i would buy CF again and think i will go Mcleod.

i have found a fairly good price online here for the street twin

http://www.byunspeed.com/product_info.php?cPath=2902_359_1343&products_id=5779

this single disc part seems to cost more on this and a few other sites

http://www.byunspeed.com/product_info.php?cPath=2902_359_1343&products_id=7797

my car has afr head and cc305 cam

now for a few questions
1) are there any good reasons to not go for the street twin? or is there a better solution
2) anyone use this site before

now lastly my limited slip does not limit so much anymore
this is an auburn (cone style) LS unit in 4th gen right?

thinking about getting the strange S60 rather than rebuild, as i would be left with the same crap rear end, anyone used one of these rear ends, will they fit alright with a lowered car?

thanks