Eddy 1405 tuning advice

Got a chance for a test drive. It's way better, but still get bog/stumble/backfire/surge. I left vac gauge hooked up for drive, so I'll list my readings.
Also it's down on power compared to prev rods. Could spin wheels with ease on previous rods.

Idle in park 750/13"
Idle in gear 675/10 1/2"
40 mph/2000rpm/13" vac
50/2500/13"
55/2600/11"
60/3000/14"
All above readings were in cruise (not accelerating)

Stumble/backfire at 55mph
Surging at 38mph cruising
Bog/surge on accel going 60 mph.
As I mentioned, it is way better, not stalling and surging has lessened, but down on bottom end(I think, lack of wheel spin) I didnt touch the timing either.
The 1448 I installed were 1 stage leaner in power mode and 1 stage richer in cruise.
Looks like 1446 on order, compared to the 48's they are 0.010 smaller on the needle end.
Suggestions?
Thanks