Did you order the o ring for the sender unit? Some senders come with them,some dont...
If you look online at say LMC parts manual, they show the shape of the lines...your truck has the return line back from the pump as well as the vapor line...so a 72 style set will do the job...
Small differences in shape really wont make a difference.
The gas smell in the truck should be reduced but will never really be eliminated.
When you get the truck running right, make yourself up a thin ply cover to go over the tank area and cover it in carpet...there are replacement cardboard panels available but making a cover out of say 1/4" tru ply luan will work out better in long run.
To totally eliminate gas smell in the cab, you could have removed both saddle tanks and the cab tank and added an aftermarket tank in the rear of the truck...but that in itself is a large undertaking...
You will get there soon...and then it will be on to the next item on the list.
