90 Gear Ratios

Hello everyone, I'm new to this forum and was wondering whether anyone can help me?

I have a 1988 2.5 N/A diesel 90 - that was originally a 2.5l petrol. It has had a full engine rebuild, injectors, pump etc. My question is the high gears seem too long, it has 1.410 on the transfer box and I have been told if I put a 1.667 reduction on it I will get roughly 15% reduction on the five high gears, will this be noticable? As I use it for hauling a sheep trailer in a hilly area and often have to go into low box. I don't go on motorways so never take it above 50mph.

Any advice on this would be greatly appreciated.

it will be noticeable and would be best transfer box ratio for you

Thanks for your quick reply james,I think that is what i shall do.