Im changing my motors from 1989 centre bolt valve cover style smallblocks to early "010" 4 bolt main blocks........engine builder says I'll need matching early style flywheels......can these be bought new??......or do I have to find them used??......how much would they be worth??

Those flywheels are available new everywhere, Try Summit, they have them. You also will need to change the balancers and intakes .

Yeah, Summit would be the best bet for those parts. You doin' some trick small blocks?
If you need some MSD stuff I have 2 new.

yeah bought them out of the US last year......had my guy go through them......355s, 010 4 bolt blocks, GM steel cranks, forged 9 to1s, stage 3 iron Bowtie heads,Crane gold valvetrain, 750 double pumpers......dynoed at 360hp/ 405 ft lbs....all done by 4800.......said I didnt think that was very much hp.......he said "these things make tons of torque right off idle, they'll work great in a boat......try them for a year then if you want we can change cams and spin it up to 5500 or 6 and make way over 400hp easy, but I think you'll like them"

I have a new still in the box flywheel off a 283 chevrolet motor if you can use it.

That'll get her workin' !!!