Wassup guys! New to the Forum!

[StugatzSG900]

Hi all,
Nice to be a part of a group who appreciate the original sound of rock n' roll!!!. Pleased to say i am the new proud owner of a JCM900 4500 (50w) head w/ 2X12 1936 cab. I've had a VS100r combo for the past 12 years and thought it was time to upgrade to an "all-tube" amp, even though the 900's arent really all tube...but im happy with it. Just the only thing i was thinking of doing was changing the tubes from 5881s (original) to EL34s as i heard from others it'll give it thatclassic marshall tone. i bought the amp used and the prev/original owner advised that he never changed the tubes!? I beleive this amp was built late '95. Might i add he hardly used it and its in mint condition. Question i had to those in the know was 1) what exactly needs to take place when switching from 5881's to el34's - i was told that besides biasing the amp, the transformer (original Drake) would need to be changed. Is that a good idea? Is there anything else that would need to be done? And last, what el34 would you guys recommend. My influences are all the classics from 60's-70's - jimi, clapton, Page, Iommi, Angus, Slash...etc.
My modern influences are Tom Morello - Rage/audioslave sound, wolfmother, Godsmack, Alice in Chains etc. I was told JJ's are amazing, but so are GTs, EH's, Svetlana's, Tung-sol!! so im kinda in a bind. What would you fellow JCM900 playeror anyone for that matter recommend? Much appreciated & Thanks a mill!!!