If I want to istall a HEI distributor assembly in my 69 camaro will it fit with no modification or will it require work to the firewall to fit properly? If it requires modification what is the best method? Thanks

It's really impossible to say for sure in advance. Depends on the combo of motor mounts and frame stands, as well as how far forward the subframe is installed in the car.

The one time I used a big coil in cap hei, I had to use a large hammer to beat in the firewall about a half inch. Others have said they slid right in with no problems.

These days, I just use an aftermarket small body electronic ignition. I like MSD, but Accel, Crane, Mallory, and others make good units.

I have a Mallory Unilite dizzy in my 69 SB, fits without any modifications at all, infact the head of the Mallory is smaller than the stock GM points type dizzy so there's plenty of clearance.

I have a stock GM hei
The top plate...that the ht leads press into needs to be shaved off the back
It needs to be mounted in the stock position ,,,#1 to the front and vac advance pointing forward at 45 deg angle to passengers headlight area
Even then 1 of the rear ht lead caps will rub the fire wall, in my car only just with nps for the last 10yrs +

When placing any dizzy..it will have to be be re curved and tuned into the engine.
There are many old posts discussing how to with and without a dyno