which plinth/tonearm for TD-124 SME or other

hi,
i just scored a Td-124 that i'm looking forward to restoring and i've read a lot of about their potential.

i have two questions.
re: plinth - i have a huge chunk of granite (4" thick) that i rescued from a building demolition in Detroit - and found a granite shop that can cut it and route it for the td-124 table - i'm quite certain it will be heavy - but is there any reason i shouldn't use this as a plinth, vs a good hard wood? i've also read that solid mounting it, or letting it sit flat on the plinth w/o the rubber isolators can produce good results - while i'm not new to the audiophile stuff, i am slowly learning to hear the subtleties that you guys talk about -

2) the tonearm - i was thinking of an SME 3009 - but i'm confused as to which one? the S2, the S3, the S2 improved etc.. I found a decent price on a 3009 S2 Improved, but have heard that it uses a plastic knife-edge bearing -
on ebay, someone sells the cnc bronze replacement for about 30 bucks... is this the big issue with this tonearm? or should i forget about the SME and find something else that will outperform it - or - is a better arm just going to result in diminishing returns for this table??

sorry for the stream of consciousness here - but trying to get a lot answered in one post - thanks