Does the '86 5.0 HO motor use the same flywheel ( C4 automatic),as the non HO version?
If not, is this due to firing order differences? or internal parts?
Does it also use a 50 oz. weight, or a 28 oz?
When I did the 351w swap I had to do something with the flywheel too. I don't remember which I had to switch to/from (28 to 50 OR 50 to 28), but a local balance shop was able to rebalance my flywheel. It was pretty cheap to do and since I had only run a few thousand miles on that flywheel it was the best choice I found. Didn't even need to re-surface.