Mine is also RHD, I made a hole in the wheel arch and ran exhaust down the inside of the guard.
Depends what you want out of it at the end of your build. I went standalone because it isn't going to stop here. It also has engine protection and various other nice features that suit me.
I have just removed the 4hp22 and installed a built Ford C4 transmission, original bell housing with adapter to transmission and custom torque converter. Made a huge amount of difference. Now I'm looking at MLS gasket with ARP studs, e85 fuel and a new turbo with 20 psi.