Found a 318/727 out of a 91 d150 for $200 (its TBI but was going to swap to carb so needed an intake/carb and a few other little things anyway) so I will be following this very closely.
Those TBI motors are pre-magnum roller motors (roller lifters/cam stock) and had more compression than most LA 318's too (supposedly) - will make a great base for a performance 318!