Well for the easiest fitment the FP150 for a 12v would be the best. If you plan on running a sump then i'd just go with the DF165.
You will have to get a new filler tube adapter if you go with the 150 b/c i'm pretty sure the gasser filler neck is a smaller diameter.
With the DF165 the return from the AD will just go right back into the filler neck then you can use a sump for the suction.
Either way the system you order will obviously be for the engine you have.