Do you already have tubes for this build? It looks like Bob got overburdened with a rush of orders from folks concerned that this is their last chance at having a tube amplifier.
IMO there's no point in spending money on "cheap" subsitutes for this design. Chances are very good that the output transformers will not handle the amount of feedback used and you will get oscillation and other problems. Prices are high for the original/reissue transformers because they're some of the best ever made.
It's frustrating because the Latino kits and parts don't seem to be available anymore.
For what you'd spend on new components, I'd strongly suggest buying a used ST70 and restoring or rebuilding it. You can also find the transformers alone on eBay.
There's a pair of A470's on a certain auction site right now for about what you'd pay for new ones--IF they were available. The power tranny you can fudge but not the OPTs.
I just picked up the triode PA060 from triode electronics last week. Only issue I see is the lead wires are only rated for 300v & are quite small on the B+ and they come out both sides of PT (unlike original) also, the coil is open on the bottom i.e. not covered like original.