My 383 is built and running and I have a vibration. I had called Eagle when I first bought the balanced assembly. I checked before putting it together and somehow got the wrong story. I was told it uses normal small block balance components. Well that is not true.
I opened it up again yesterday and got the part numbers, the tech help at Eagle confirmed today that it is an internal balance design.
But I don't see any good buys on a flywheel that is neutral.
Most one piece rear seal cranks are combination balanced with a front damper and a weighted flywheel.
The LS flywheels are neutral, do they bolt up?
Do the holes in any of the other styles mate up to a Mercruiser coupler?

I sure hope I haven't gone too far into Frankenstein territory here!

Looking for flywheel help. Should I have a factory flywheel machined down to neutral? Or bite the bullet and spend?

You can have a shop mill off the weights on your current flywheel.

Yes, that was a conclusion I came to after posting. I'm glad you said it though. It's good to get some agreement from more experienced folks before doing something new.
Thanks.

There is a small area on the flywheel not much bigger in total are as 4 quarters and about as thick that needs to be milled off. I don't have a picture though, sorry.

The flywheel will still need balancing after machining. Think engine shop can just drill holes without milling the wheel either way.

I'll have to see if my machinist has balancing stuff. He's an industrial prototype & contract machinist as opposed to an auto & engine machinist. I'm getting it milled flat, but it does have a couple of balance holes.
My engine guy is near my old work.
If it's not smooth it's off to the balance shop.

my local machine shop does them forvme all the time..he charges me 50 bucks to zero balance them

Real cheap to have weight taken off, real expensive to have it put on. Also aren't 400's flywheel neutral (if needed)?

Yah, but 400's use the old 2 piece seal bolt circle and tooth count

It's reassembled and hooray, the shake is gone.
The machinist who balanced it must have done so with either a neutral wheel or nothing. So my summer is back on.
I have only run it on a stand and out of water on the trailer. I'll report back any oddities in use.