The 40 and 41 trucks were similar to the sedans back then as far as grills, etc. I agree the 40 has a slightly better look, however you have to change both fenders, grill, valence and possibly the radiator support if memory serves me right.
whether to restore rod, or drive as is up to you.
If the truck is close to complete and in good shape, I would do a resto-rod - basically stock exterior with an engine and trans swap as well as the rear. That way if you wanted to put it back to stock you could.
If the truck is not complete and you are intent on rodding it, my suggestions are as follows:
MINI headlamps recessed into the fenders (can also use new VW beetle)
Channeled by 3"
Sectioned by 2"
drop axle from sid's vs the Mustang 2
loose the hood side panels
2" wider rear fenders
shaved door handles
lots of finned aluminum goodies under the hood
SBC with Edelbrock intake and 6 97 EFI carbs on it -
http://www.mooneyes.com/MISC/drive.htmllake pipe headers with exhaust cut-outs
Tremec TKO600 transmission
single piece front windshield
reproduction bomber seats