Need someone/ garage who knows way around a G

Hey guys so due to time I don't get to work on cars so much anymore and rely on garages. My 460 300gd lwb has recently come out the garage and not happy with few things. Brakes are jumpy even though recently changed most parts and I know they aren't very fast but at full throttle this feels like I'm only pressing the gas pedal half way down, 30/40mph is a struggle on a straight. and you might also have read about my gear issues (1st/2nd where 5th/reverse should be) 

It needs a going over by an experienced eye, any recommendations? East Midlands area preferred but don't mind getting transported. I sell wall aquariums so I can pay in cash or fish tanks :)