'65 MGB FIA Race Car - technical woes - Urgent advice needed please!

[Cadence]

Evening all,

My car has been under wraps since the last meeting in October last year. I decided to do a track day on the spur of the moment and checked the car over before loading the trailer. All seemed well and it started just fine. The issue I've now discovered is...

- I have a catch tank with connections from the rocker cover and crankcase breather. The catch tank has a K & N filter attached.
- when starting the car I noticed quite a lot a wispy vapour entering the car - it's coming from the breather tank K & N filter. I cleaned the filter
- I took the car for a 20 minutes run along the local lanes (my car's road legal ish) hoping that this would cause any moisture to vaporise
- there's plenty of power and good pick up, oil pressure good, water temperature ok, no mayonnaise in the rocker cover filler, oil looks clean and no bubbles and my coolant hasn't changed colour to indicate the presence of oil in the cooling system

Yet when I stop, it looks like someone's having a fag under the bonnet. The catch tank is filled with fumes as is the rocker cover.

I have a track day on Monday and at a family do most of tomorrow so there's only tonight to determine whether it's fit to go on track on Monday.

Any ideas what the problem (if any) could be? I'm loath to go blasting down the Hanger Straight if the omens say, for example, a piston ring has failed. I'm no mechanic and don't possess a compression tester so cannot test this.

Starting to panic - help gratefully received.

Cheers