Should I cut the frame???

[BaroneDog]

Doing a test fit on my 67 LQ conversion. Headers (Thorley 323Y) are almost touching on the passenger side and significantly interfering with the frame on the drivers side. Reading around a bit, it looks like the 1967 year frame rails are a bit wider than later years. It looks like I will need to trim them back a bit to get enough clearance, but figured it would be worth asking the community to see if anyone else ran into this and if they went a different direction.

Moving the engine back or up will not fix it. I have the motor about as far back as it will go. Cannot move more than about another 0.5" before the header will hit the firewall on the pass side. Also, I tried moving the engine up (as if shimming or using a DD slider which is a bit taller) but that did not provide enough clearance either. Other thoughts?

First photo below is pass side with header mounted (but no gasket) and the bottom two are drivers side but the header could not even be fully seated on the head due to frame interference. Ignore the blue tape (just trying to prevent scratches on the shiny new headers!).

Also, for anyone who has the 323Y headers, what type of spark plug wires did you use? Looks like a tight fit.

Many Thanks!