KT150s in Audio Research Reference 75 (non SE)

I believe Minor1 is correct.  If iit was my amp I would call Audio Research and ask.  Since they design and build them, they will have the correct answer for you.

I spoke with the Audio Research technical expert about 2 months ago.
I also spoke with George Meyer rep and the actually do the upgrades to SE and also said you should not use KT 150s without the larger transformers and other work. 

I believe them

enjoy

Im just going to hold off and upgrade to SE first.
Thanks all!

I spoke in person to a very highly placed ARC representative (whose name I promised not to reveal but all who follow ARC would know) in late 2014 just around the time that the Galileo series was in production and prior to the release of the SE amp versions (which the rep hinted would come soon). I asked if I could drop KT150s into my Ref 150. He said that ARC had tested the KT 150s for months in the standard models and that there would be no harm in dropping the KT150s into my amp although he also said that ARC had not obtained sufficient quantities of the tubes to sell them direct. He suggested that I wait for ARC to sell them in the future or, if I was in a hurry, to purchase from Upscale Audio. 
I did so, biased the tubes at the standard 65mVs and am currently beyond 1,800 hours with nothing but satisfaction. Months later the SE series came out and, of course, contained modifications specifically designed to accommodate the KT150 tubes. Nevertheless, I understand from those who have compared the SE to non-SE amps with KT150s that the tubes alone get you most of the gains in sound that the SE provides in a combination of the KT150 tubes and hardware upgrades.
I am sure ARC would never officially say this now--after all they want to sell the SE versions--but look at the posts here on Audiogon and Audio Aficianado in late 2014 and early 2015 regarding the issue and you will see a number of non SE owners dropping KT150s into their Ref series amps. All came back with favorable results and no problems were reported.    

@gpgr4blu 
I really appreciate all the information.  I believe everyone, so it's a bit perplexing. 
In the end, they simply won't bias in my Ref 75.  I did get them matched for the Ref 75SE from TheTubeStore.  
They all have stickers that say perfect pair and "81" is written on the labels.  
Nonetheless, they won't bias properly.  
So, I'm not going to run them.  I've put some new KT120s I had in, and they biased quick and easy.  
I'll just look to upgrade to SE soon, and keep the KT150s as spares for down the road. 
Thanks all.