I heard Powell was benching around 150kgs with Frater when he tore his pec. Im pretty sure ive seen a video of him and D.Brown repping 6s on bench at around 120kgs. All from memory tho Im afraid!
In terms of cleans, there was a presentation given in the UK quoting various sprinters PBs. Linford 152kg clean / 270kgs squat(maybe)
C. Jackson was around 145kg clean
J.Gardner 142kg clean.
Ive also heard on the grapevine that Devonish half squats 270ish kgs.
If thats any use to you?