90 V8 Supercharged Auto or Manual Gearbox?

here's hoping someone can put my mind at rest......

i have just bought my first land rover - a 1986 90 2.5 petrol pickup

i have driven a TD5 which seemed OK - should i expect similar performance from my 2.5 petrol?

now for my dilemma! i also have a V8 engine to fit to it but there's a little voice in my head telling me not to because i don't know what i'm getting myself into! i live in Ibiza and my options are:-

1. Sell the V8 & drive the car to Ibiza as it is.
2. Keep the V8 and fit it next year if i don't like the 2.5 petrol (bearing in mind it will cost me €1000 to bring it back to the UK for conversion.
3. Buy the additional parts i need (mainly gearbox) and convert it now!

I know that the sensible choice would be a 200TDi or 300TDi conversion but it doesn't make financial sense right now for me just to improve fuel consumption if performance on the 2.5 petrol is similar to a TDi (as people seem to suggest). As i understand it, the fuel consumption on the 2.5 petrol is similar to a V8 (12-15mpg) so i figure i might as well drop the V8 in for a laugh if it's not too difficult as i have most of the bits:-

3.5 Rover V8 from an SD1
rebuilt to lowest compression (for supercharging)
sprintex supercharger
edelbrock manifold
all the ancillaries

what i don't have is a gearbox. i'm pretty sure it's fitted with an LT77 but this might not be up to the extra power. i have done a little bit of research and i think i have two options:-

Option 1: R380 gearbox and LT230 transfer box from a defender or discovery. i would also need a V8 bellhousing (if from a diesel) and a long stick conversion (if from a disco). do i also need to change the input shaft if it's from a diesel? anything else i need?

Option 2: Automatic gearbox and transfer box from a late 80's range rover. do i also need an LT230 if it comes with a borg warner? i have been told that the RR autobox has a longer casing than a LT77 or R380 - is that correct? and is there anything else i need other than the gearstick and trim parts?

do i need a particular torque convertor for either engine?

the extra performance is a bit of an extravagance in a country that is only 45km end to end but the supercharged V8 is very tempting as i am used to driving fast cars - anything that bridges the performance gap for the landy will be welcomed!

i don't intend to do the work myself and i have a good mechanic.
however, if there is an experienced amateur on here that would be interested in doing the work then i will be happy to pay them rather than a garage so let me know!

also, let me know if there is anyone on here that can sell me a gearbox/transfer box/V8bellhousing or would like to buy one of my engines! or swap the supercharged V8 for a good 200Tdi or 300TDi maybe?

so what do you think???

many thanks.

b.

I would forget the forced induction bit,this can be a very expensive and time consuming thing to get right.I would go for a 3.9/4.2 classic RR engine and its ZF 4spd autobox.This means lots of standard parts,(not expensive now either) and its a well known conversion - lots of good advice should be available.Keep its 14Cux injection system,maybe a more lively cam - then all you need is a performance ECU from Mark Adams.
This will be a quick truck in this form,run it for a while to sort out any bugs etc,then think about forced induction.Or had you considered Nitrous ? This might be the quickest and initially cheapest way to go.But this is where the ongoing costs mount - too much thrashing and it will go bang,depends how many times you are willing to nail it back together !
BTW I have a complete single turbo conversion off a 3.9 that I never got round to using if you are interested.

thanks for the response - i'm having more serious second thoughts on my V8 now anyway!

can anyone tell me if the 2.5 petrol will give similar performance to a TD5?

i know the economy will be much worse........