Yeah. I'm confident in my welding so if i go with the conventional HR crossmember mounts it'll be sweet.. if i do something custom / one off then i will ring up an engineer for it.
As a few have said Nick, dummy it all up tack it all, drop the crossmember out and fully weld. We did my old FC this way after I bent a crossmember Don't ask..... was not a fun day.
Speed and Style........... One day I'll get the speed bit.