Are you anywhere near San Diego?  I teach an amp building class and my next class we will build a lighting.  As for the transformers, I have used different ones and built the amps side by side in class then played the amps side by side when complete.  In one case we used all Weber components (which lots of people complain about) in one amp and a combination of Heyboer and Mercury Magnetics in the other, and with all other components up-graded.  The difference was very slight.  Playing them side by side, I would have chosen the up-graded one hands down, but playing them in different locations at different times you would say they were the same amp.  They both sounded like Fender 5E3's.

I have found Ceriatone components to be high quality.  Don't subsittute or change anything on your first build.

Hope this helps.  The Big Goon

Be sure to buy a matched quad of power tubes.  Ther is a way to use 2 matched sets putting one matched set as the center 2 and the other matched set as the outer 2 but that is a bit risky and you may have some noise or other problems.  There are a few tricks to figuring out if noise problems are caused by mis-matched tubes.  ther are verbose explinations on the web.

This is a Rock It Kit