I am a collector of WWII military vehicles. As a collector, I would suggest keeping your DUKW original. It will be worth more money down the road to other collectors that way. Tour DUKW operators are not very concerned with being original, but making money like any business should be.
I have owned my DUKW since 1991 and have been out in the water a lot. The first year I went out in the water 104 times!
I have never had a power problem nor a problem with the original 6 volt electrical. Yes, DUKW's like all WWII MV's are slow but they were not built for speed. The 270 is a bit under powered. I wish I would have bought a DUKW when I was 15!!! You can look forward to many years of fun!
Here are some examples...
This was in the Columbia River at the 1996 MVPA Convention
Firi ng my 37MM AT Gun from the back of my DUKW! (blanks)