Not long done the T5 conversion and took it for a play and ever since the oil pressure has been fluctuating really bad to the point today when the light came on and a grinding noise came from the bottom end and also doesn't feel like its got power down bottom any more. Only just rebuilt top end but didn't touch bottom.

What's the cause of the oil pressure rising/dropping and what are symptoms of bottom end bearing?

yes usually its from bottom end bearings having excessive clearance, but could also be a blocked oil pic up of bad oil pump..

I thought about oil pump as I had the sump off for a week or so. Seeing that that's a motor out job I'm planning on building another motor and using my T head to putting a cms 2a cam in it but what can I do the bottom end to have more low end torque??
I have rebuilt a few motors but haven't touched the bottom end any tips on what to do?

doing a freshen up on the bottom end is easy and relatively cheap and feels good. just do it and throw your ticky head on it and all should be sweet. just take your time to do it right and its all good. i did all the bearings, rear main seal, timing cover seals, honed the bores a little for the new rings new and a few other bits. painted all the brackets and block to make it look flash was fun and relatively easy if you take your time.

It's fine on cold starts but when it warms the oil pressure drops really bad and the warning light comes on and beeps, also with light throttle it sort of grinds/hums but not with full throttle as it builds the pressure up a little but drops instantly with deceleration.

My thoughts are that its a bearing as it sounds like a dry pulley does.

I dropped this motor in around 6 weeks ago now with a reco T head and all bolt ons are new but didn't touch the bottom (should have but didn't) Iv got a couple spare motors so should I
A: build another bottom end and put ticky head on it with new head gasket and bolts or
B: rip motor out leave head on and fix that bottom end?
C: smash it till it dies and put the 5L in.
Only problem with c is having to rebuild the V8 as its in pieces and I'm on a tight budget ATM.