Engine conversions `help`

Hi, With reference to my last post of problems with crankshaft pulley. If this proves to be a bearing failure or bent crankshaft then it`s terminal.
My current engine is the 19j 2.5td and even though shes just clocked 150,000 miles she runs great and pulls well. My question is can anyone recommend or know where i could get my engine converted to either 200tdi or the 300 but still use my current lt77 box as it`s great. I would do it myself but i have not the facilities or major tools to do the job. I live in the south wales area, so i`m basically looking for someone to supply engine and carry out the conversion at a reasonable cost as the landy has been rebuilt on new galv chassis, repaired doors, new seats front an back etc etc etc.
Any info welcome

I dont know about in wales but I am in Essex and have just had my old NA converted to 300tdi and the whole lot with engine cost circa a grand but a good job and the LT77 does go onto either 200 or 300 we just left the 300 bellhousing on and drilled and tapped additional fixings from bellhousing to engine. pulls like a train now best thing I ever done to the old NA.