erm...a lot and a long time
TBH it probably hasnt taken that long its just i bought a house and have many times put the car aside to concentrate on other things. think its 2 1/2 years ongoing with the v8.
as a conservative estimate i reckon just the engine conversion and all the other changes around it has cost 5k. but thats with silly things like a £400 hydraulic clutch release bearing, £700 on twin plate clutch and flywheel etc so could be done for less
the hardest part of it all id say is the headers as one side needs to be made to go around the steering column, the ones ive gone for make that easy but have forced me to ditch the brake servo and go for a wilwood BMC with all custom brake lines etc.
if you were thinking about it (and i know other people you know well are ) i could help a lot and get the costs down