For driving a single SV83? A strapped-triode Mullard EF86. It sounds mindnumbing, SCARY good. In strapped triode, it only produces about .1% distortion when the SV83 hits zero grid voltage (18V p-p), and has a very low noise floor and extremely low heater hum induction. It was never meant to drive power tubes, but the SV83 is so easy to drive that it can pull it off quite easily.
But if you've already got plate load chokes (was that you?), they'll not have enough inductance to load an EF86 down to the lowest frequencies, with it's higher Rp. Off the top of my head, about 120 Henrys would do it.
Second choice is a 6922/6DJ8, unless you have a rather hot source (3 volts or more), in which case I'd definitely use a 5687. If I was using a preamp, I may even try a 5687 SRPP stage (has very low gain).
Eddie