im using a hammond choke and OT with a weber PT for my KT-88 build

For my 50w ceriatone OTS with 6L6 tubes, I've used a hammond power transformer (model: fe022798) and choke (model: fe125c1a) The transformer has all the windings needed e.g. 6.3V and 5V. The latter used for the relays in the amp.

For Output I bought a Mercury Magnetics FTBO. The MMs are a little hyped and I'd probably be just as happy with Niks output transformer or Hammond or Heyboer ditto. Go for a 'Bassman' capable version preferably with multible secondary windings (4 ohm, 8 ohm and 16 ohm) for relevant speaker cabinets. Even though, I only use the 8 ohm tab on mine.

I've read some posts on Ampgarage.com about Niks power transformer being a little underrated. I don't know if this is true (or would be relevant for your specific application), since I ordered my kit without trannies and bought the above mentioned transformers locally in order to save expensive fraight costs.

You can be quite confident that Nik's amps will deliver the goods, once you allow a 'burn in' period of 50-100 hours, which is common for all amps. 

Has anyone used Heyboer trannies in their Overtone?

correct me if im wrong, but i think you could just use the filament heater 6.3V tap for the relays. My non ceriatone Dumble build does this and works fine

Does it matter if the PT that I want to use has 358v but the layout shows 345v?

Also, the layout shows 60v , but the PT I want has 53v?

Don't be disappointed when you get the amp assembled...you gotta allow it some burn in time, around 40-100 hours before it 'opens up'. I you don't have time to play the amp connct a CD player instead.

A lot of people have made the mistake to do all kinds of mods to soften the amps sound etc., only to realise that after the burn in period, the amp tone will change somewhat.

I use an ol' discman (or IPOD) connected from the headphoneout on the discman to the input of the amp, where I would connect a guitar.