LS1 header measurement needed

[64skylarkls1]

Can anyone take a measurement how far the rear two tubes stick out from the LS1 head mounting surface on a pair of long tube headers?

I have a very different set up in my 64 as I modified the firewall to fit the LS1 steering column and pedal assembly. One of my steering u-joints is quite close to the LS1 exhaust mainifold. I'm wondering if I will have an interference issue with going to long tube headers.

Thanks!!!!!!

Gene