1991 Nissan 200SX review from UK and Ireland

Engine is making a BAD ticking/knocking noise. Happens only when I try and maintain a constant speed. Only above 2000 rpm.

Have been told by Norris Designs over the phone, i.e. they haven't heard it, that it is the big end bearings, although I went to a Nissan dealer for a diagnosis, they said it sounds 'top endy', but without a full strip they can't say for certain.

Have been to a knowledgable friend who says that big end problems make the most noise under acceleration and when revving the throttle. However my noise doesn't appear under acceleration, I can accelerate all the way to 100mph without hearing noise and with plenty of power just like before the noise appeared. When I back off completely i.e. foot off the accelerator, the noise isn't there, it only happens when I try and maintain a constant speed with the engine above 2000 rpm, so I have been driving around at no faster than 35-40 mph which is about 2000 rpm in fifth.

Norris Designs said that if it is the big end, then it is cheaper if I replace the engine than rebuild it.

I figure if it is big end, then I need new engine so any damage I cause by using the car doesn't matter.

Anyone got any thoughts?

Anyone got much personal experience with working on them that might know what it is?

Anyone know of a 200SX club in UK? I know of Swedish and Australian clubs and also of 240SX US club, no help.

Sorry to use carsurvey like this but I am desperate.