$4900 is a pretty good price for a running M5! That said, depending on your budget (and how much you want done in one go) it may be best to bring it to one of the specialists in the GTA.
The S38 is a unique animal - get the right people rebuilding it, but be warned that it will in all likelihood cost a lot more than what you paid for the car.
1998 328i "M-tech"
2001 TDI Golf. 1300km/tank commuter. Boring, slow, cheap.
1991 P-car: 964c4 Let the porcupine jokes commence.
Gone: '99 M3 vert, '98 M3 sedan, '91 E30, '89 E30, '87 E30, '91 Euro M5, '93 6-speed Corvette, STI v8 swapped '98 Impreza, '73 2002, 2004 325iT