I'd try to tweek the TD first and get all the power out of it that its capable of. I would hesitate to go through all the work of swapping engines, etc it you're frustrated with the TD's power. Why? You may want to consider an all-together different vehicle if the mountains bug you.

Most of us love these things and they are great on the highway. I've not had enough mountain experience with them to suggest one way or the other.

Don

__________________
DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed