Jim,

I just don't know the effect of a lathe bed being off level. I guess that the more important thing is that there are no forces distorting the bed. To my mind it might be more practicable to set up with a cheaper level. but before bolting down put the bed on some sort of metal filled epoxy cushions that settle out any twisting forces. Then, when they have set can the fixing bolts be tightened.
As I have said before, I am not an engineer, so some of my thinking is 'outside the box'. I am in the middle of raising my lathe off the tray to give me more room to clean up. So when I have made the platforms for the headstock and tailstock I will either need to get them surface ground or concoct some thing else like liquid metal shimming.

I am certainly following this thread for advice.

TTFN

Rob