Hi, any help appreciated 200 tdi.

Hi I have had a defender 90 for around five month. ( 200 TDI ) I have been told the engine was rebuilt, bored out, new big ends etc around 40,000 miles ago. (This is the 1st defender I've owned and not drove any other)
It seems very slow to accelerate from a standing start especially from a standing start at the bottom of a hill. I loose 1st gear immediately and 2nd gear isn't enough revs.
Would an allisport intercooler sort this or do I need a turbo VGT? or is there something much cheaper than these options.
Any help or advice much appreciated.
Thanks

Defenders are different to normal cars, What size tyres are on it .

Also what's the ratio of the transfer box? Is it ex military?