Seems from reading the M42 has a lot of tuning potential as an engine which is attracting me for my little project over the M43 or M44. Seems little comparisons done between the blocks as mostly people use them in the car they got or if change do so to a 6cyl or more.
IMO - Changes to the car you've done and plan sound ordered and probably about as much as is economically sound before going to a bigger lumped vehicle.
short shift perhaps ? Slight aside anyone fitted a Z3 gearbox to M42 ?