you absolutley CAN fit these engines without cutting the firewall, but there is a LOT of hammering to get it back far enough for where mine sits. I cut my firewall just cos it turned out easier to do that than keep hammering for where i wanted it. I was under the impression ipra couldnt do any modifications to the fiewall?
As said, putting it forward means there is no need to touch the firewall, and a w series would mean no modding to the tunel either. The boxs have different shifter location points, all are interchangeable, but they differ by something like 4 inchs from one extreme to the other
Beaus is running MUCH further forward than mine and chickens ( pretty much exactly the same spot give or take few mm ) and he hasnt had to hammer the firewall, and he used a fwd beams engine. He went custom clutch flywheel and shaved bell housing and a few other mods.
as stated i would love to be of help, anything you need just let me know