Two questions. Nothing serious but I'd be interested to know whether this is normal:

(1) On my TP sedan, there always seems to be some oil on the rocker cover near the hold-down bolt at the filler cap end. I keep wiping it off but it keeps re-appearing. The filler cap seems to seal fairly well. Could it be getting out through the bolt hole? If so, how can I stop that? (it is a low km engine, so valve stem seals not suspected and I've cleaned the PCV valve)

(2) When I start the engine on this sedan, there's a sound of rushing water behind the dash. It also happens when I accelerate or back off. I remember my TM sedan (also with carby engine) used to do it even when new but my TP wagon (with EFI) doesn't. I could understand it if the heater was on but it is off. Does your 1st Gen sound like a whirlpool?

I will be replacing the valve stem seals on the wagon next weekend so will learn more about rocker covers then.

Is the thermostat fitted

Yes, a new one. By the way, the water flow may be in the engine bay and may only sound as if it is behind the dash but it is very noticeable, like a washing machine emptying.

sounds maybe like underfilled coolant or air pocket in the system maybe.. sometimes that can cause it. If there's a sound similar to gushing water that you hear when the revs are around 2000rpm or so, then that is most likely a slightly loose timing chain tensioner, which is about a 5 min job to adjust. I used to have a gushing water noise at about 2000 rpm when i was coasting along or accelerating, and after adjusting the tensioner, it disappeared.

Other than that, try the ideas magna buff suggested :D