A while back i had to make some changes on a street rod that faiked provincial safety. The fuel line was almost touching the exhaust. Original builder used something similar to hydraulic hose,1/2 inside diameter. i rerouted line forward up over frame rail near rad, then outside frame rail to rear of vehicle.
Its awesome you are helping your buddy out, giving him some joy at the end of his driving carreer.
I too have deteriorating eyesight, but blindness is not in my near future, i hope. One doc said macular degeneration, other one said something else that i cant recall. Regardless, you are helping someone live their dream!!
