Due to excessive wear of the bores in the cam towers, I am in the process of making and inserting bronze bearing inserts.

So far, my search for a machine shop capable of align boring them has turned up one shop in Ohio, JCM Machine and Coatings.  I am in Virginia.  Though I have done it before, I am not delighted by the idea of shipping my head off somewhere.  I'd much rather see their operation, look the man in the eye, and so on.

Does anyone know of a shop that can do this work (and do it brilliantly!) - anywhere, but local would be ideal?

Eiji at Datsun spirit might be able to help

Yep, I was going to suggest Datsun Spirit also since you are in VA.

I'll reach out to him and see what he says.

Thanks

Why the line bore ? Can you swap out towers ? 

I own a Sunnen line bore machine and I would be trying different sets of towers before I went that route. Setting up the boring bar to bore the correct ID and getting the head true to the machine is a major PIA. 

@madkawI decided to start a thread for this project to explain some of the work I am planning.  I will reply to your question there.

It's titled: Another Z to see the roads again...

@DerekThanks for that input.  My concern is that used towers are unknown quality/condition.  New bearings and bored to specification, assuming it is done properly eliminates any problem of a loose bore (loss of oil pressure, flexing of the cam, maybe loose engine noise which I hate).  More on the other thread.

How will you retain the bearing? Interference fit?

Yeah - .0015 - .0020 interference. 

The coefficients of expansion are ~12.5 for aluminum and ~9.76 for bronze.  If the towers see a temperature change of 120F (bearings made at 80F, engine warms to 200F), then the bore in the towers would increase from 2.0400 (1.8898 + bearing wall thickness of .075) to 2.0431.

The bearing OD would change from 2.0415 (2.0400 + .0015) to 2.0439, so still an interference of about 8 tenths. 

I'm beginning to like @madkaw's suggestion of sourcing another head.