#3
Yes, the 4558 is a dual OP-AMP chip wheras the 741 is a single op amp
you would need to change the stripboard layout at least. Also, the 4558 is probarbly different electrically, requiring different part values. I would reccomend the TL071, from what ive heard, its like a 741 but it has less noise

Happy Building!
Gear List:
Ibanez S320
Lavey LV200
Squier Stratocaster Affinity HSS
No-Name Wesley Fat Strat copy
Peavey Rage 158
#4
Yeah, I heard about the noise, thats why I was thinking of making the switch. Crap. That was glaringly obvois. I should have caught that myself... Didn't sombody make a versoin of the 250 with a 4558 on here before? Maybe i'm just losing it.