Tube guitar amp output transformer - Is bigger always better?

I'm working on building a 100W Soldano SLO clone amplifier and while researching transformers I've read some things like bigger output transformers have more clean headroom and give tighter bass response, and I wonder if there are any other features that make a certain transformer good for a certain amp build?

I know everyone seems to recommend the O'netics Hi-def transformer for these SLO clone amps which costs nearly $300, but I have an opportunity to buy a used OR120 OT for much cheaper and it's actually larger in size than the O'netics. However the sound I'm trying to get out of the SLO is very different from the fuzzy OR120 sound, so I wonder if you can see any potential problems with using the OT from one of those amps? Any thoughts?

you want that clean, sustain sound that Dickey Betts gets out of his Soldano at Great Woods with Warren Haynes?

yes a bigger core means more bass, but you can kill that with the tone controls,

unfortunately transformer sound is hard to predict so you just have to experiment, which can get expensive,

i would go for the orange, 300 is too steep, better off putting the savings towards some Nos tubes from KCA.