The cam locking tool works on all M42/M44/M/S5x engines regardless of chassis.
I think we bought the 2 tools off ebay for $40 shipped.
And yes you need to remove the lower cover to ensure you have the timing set correctly. I mean you rebuilt this once, and you didn't get it right, now you want to take more short cuts on the second time around. Did you not learn your lesson the first time?
"If a job is worth doing, its worth doing right the first time"
Your on your second time around, lets try to get it right this time.
Get the proper tools, follow instructions, take your time, and enjoy the reward of a good running engine. Either that or just take it to a shop.