1987 Overhating problem

1987 Supra turbo. ~70k miles. Likes to overheat on random occurances, mechanic is clueless. Any ideas?
Also curious as to a "Whooshing" sound like running water, that occurs under relatively hard acceleration (Problems usually occur with heater running)

Is this normal, or?

Any suggestions are appreciated, thanks.

The "waterfall" sound in the dash? It means you have air in the heater lines, it could just be that the cooling system simply wasn't properly flushed and refilled or it could be a sign of a BHG starting. Either one could leave air pockets in the system and cause it to overheat at times. Are there any other signs (milkshake in oil cap, dissapearing coolant, white smoke) of a blown head gasket?

No signs of the head gasket being blown.
The coolant has been bled and flushed about 4 times by now, as that is what I originally thought, Various little pieces have been replaced as well (t-stat, radiator cap other bits that skip my mind)

did u burp the cooling system? also napa has a neat little thing that u use on the radiator that lets u kno if u have a BHG or not? did u do a compression test also?