Who told you that jz engines are "bolt on fit" on MKII?
You might to relocate the radiator to accommodate the engine! '73 MKII came with 4cyl 18R engine, had it been 74-76 that came with 6cyl 4M engine then the story would have been different.
3S-FE (of course petrol) was your best option..
Contact Shamim sb (02132771427) he had Japanese MKII suspension parts.. make sure to get all original parts (incl bushes, ball joints, tie rod ends, idle arm, steering arm)