It will bolt up to the 12v vr with out a problem. However the mounts to the chassis will take some working. The o2m trans use a magnetic speed sensor so unless you swap a matching guage cluster in your mph will not register. thats my 2 cents
I didn't swap a matching guage cluster in and my speedo works perfectly. Just gotta mate up the wires coming out of the speed sensor to those in the harness. No biggie.
To the OP: Don't compare a lightened flywheel to an O2M swap. The swap might cost you over $3k! It may not....I had to source all of my parts along the way, with hardly any help...so I paid stealership prices. Plus I got a very very low mileage o2m. I never did add up what I paid for what. But the trans/shift box/etc was over $2k.
My build thread was lost in the new forum software but that will be searchable in about a week....keep an eye out for it then.