You can check out PinkFloyd's site for X mods http://rockgrotto.proboards39.com/index.cgi
Depends on how much you want to spend, and how much work you want to put into it. I would consider stuff such as:
replace electrolytics with Panasonic FMs, as long as they aren't on the outputs of voltage regulators, which might need more ESR to be happy get rid of any tantalum caps as these tend to fail as a dead short... replace with Wimas suchg as MKS-2s replace PSU diodes with Shottkys, such as 11DQ10/31DQ10 make sure opamps are bypassed well... 100uf Pana FMs right on the V+ and V- pins to ground, possibly something like 3.3nf MKP between V+ and V-, you could also try Carlos FMs snubbers (0.1ohm SMT resistor and 3.3nf ceramic COG or NPO SMT in series, between the pins of the FMs). Leads on radial caps as short as possible. replace coupling caps with film or BlackGate NX or K series, Cerafines/Silmics, Nichicon Muse, whatever floats your boat