2.8 gearbox is going to shit itself royally with 300 bhp going through it. I'd suggest the MT75 as it's stronger. The ratios aren't so nice but you can't have everything. 7000 rpm from a Cologne will need a main cap brace as said, as well as ARPs. With a lot of mods, 300 is achievable but it is probably cheaper to twin turbo it and keep the revs down to standard.