2800Kv on 4s even in the HET fan will be very mild, in fact I would expect only 30-33 amps per fan, you could easily run both on one battery pack!! Having two 3700 packs is overkill for your setup.

Best to get a pair of 2W20's if you want to stick with the stock fans. The 262 however really deserves some nice sounding fans in it, a pair of Wemo's with 2W18's will get it moving out really well, 1.5kg thrust per fan on 4 cells at 58 amps, your packs will be perfect for this setup.

A customer built one of these and it flew really nicely on the 2W18 setup.The old GWS 262 was a bit of a handful at low speed, nasty stall, I ran mine (when they first came out years ago) on GWS fans with 3900Kv blue motors, 4s2200, was clocked at around 100mph, flew really well.