Yeah it's a good trade. M15a gives good economy & hence you'll love the throttle response.
Clean jdm engine the one pulling 170-180psi compression with not a single bolt open costs 35k & worn out one's are sold around 25-30 range.
Rest depends on you, a good quality oriented swap touches 60-75k with all new hoses, radiator, coolant, clutch plate, good liquimoly lubes.