when my 225 blow up, I swapped in a Buick 231 even fire V6,just had to rebanance the flywheel. go with that that works. 350 maybe to much for the dana 18.the 400 maybe to long and make for a short driveshaft.
Rubicon Rich ,05 TJ Rubicon: PatriotJeepers.com
86 CJ7 258,T18,Scout Dana300,twin sticks,Dana44's,4W Disc, locked,35's,YORK OBA,Warn 8274,fullcage.
51 M100 1/4 ton Jeep trailer