MXDL SA-76, help with Driver upgrade

Just got this one and am already scoping out a driver mod (you all know how that goes!!). Nice light overall, totally rebuild-able... nothing is glued or even soldered (outside the LED wiring). Its a true Lego / Tinkertoy, and I think a good mod candidate. It only pulls 2.15A from a Sanyo 18650, and has a noticeable PWM on MED and LO modes. The driver is a 26mm board. So I am looking for a drop in replacement with a higher HI and with MED and LO modes.

Are there any good replacements out there for this DC-DC circuit? I don't need 8.4V capability (but it would be nice to have), as I do not yet have IMR cells this size to accommodate.

thanks!!!

Hmm... thats what I thought. Not many 4.2V options in the 26mm diameter.

Plan B is to de-populate all the SMT components and use that driver board as a "pass through" dummy and piggy back it with one of Craigs 8x7135 boards. Theres more than enough space in there, and if I sandwich it right it might even end up a lower profile than the OEM circuit with that toroid.

What do you think?