Sequential box would be sweet mate, but there mentally priced.... did you enquire how much there offering is ?
I was thinking about a SQS sequential conversion - not a true sequential box but it simply converts the gearstick end to give the cables the right order. It has a microswitch that senses when your changing gear...i'm guessing it could be used with no lift shifting to change up but you'd have to use the clutch to change down.
Maybe the switch could be wired in parallel with your clutch switch to create a ignition cut long enough to slot in the gear - i'm betting Bill would know if it could be done