For EL34's I'd recommend a couple of different things to tighten the rythmns...Keep in mind this what I've found in a DSL50 and Peavey VTM 60 modded for EL34's so it may not translate due to the Rectifiers voicing...
Avoid Ruby BSTR and Tungsol EL34b - They are a near 6L^ and really choke out the mid range hump of the usual EL34.
IMO Slimmer bottle EL34's - Winged C and JJ EL34's (Not the L's) will help boost the midrange (think crunchy and smooth) and tame a little of the rectifiers low end while still retaining a nice shimmering top end that reacts well to presence and treble.
Couple of other things I only recommend if you are truly happy with the platform...Preamp tubes - Mix and match to find you favorite combination. What I like you may not. I've run so many through the years that I have a good understanding of what I like in each amp, for each position. Tung Sol, Penta, JJ, Sovtek, Mullard RI for the PI I usually use the most balanced tube I can find. Cab - If your using an oversized rectifier cabinet, go with a tradional or cab of similar dimension IE 29X29X14.5 ish. The reduced space really tightens up your bottom end. Speakers - stick to a mid heavy speaker (V30 and Peavey 1200 loaded in 5150 cabs) come to mind. Avoid GT12T 75 they are a very scooped speaker. OD's - 808's and Modded SD-1 gain =0, Tone 11-1, level maxed or to parity.