The crankcase absolutely has to be vented some place, otherwise it is going to blow oil out everywhere (mostly the rear seal).
But your early TR4 should have a road draft tube on the side of the engine, and a vented cap on the rocker cover. The 'sealed' system with the tube to the carbs did not come in until CT23594.
In theory, the vented cap helps keep the oil cleaner; at speed the air rushing past the road draft tube pulls fresh air in through the vented cap, thereby dispelling the blowby gases that could later condense to form acids and sludge. In practice, I'm not sure how much difference it actually makes.
But, since pressure buildup in the crankcase is a primary cause of blowing oil out the rear seal, it seems like a good idea to me to keep some sort of vent on the rocker cover.
Hooking it up to the air filters might help reduce pollution, but IMO isn't going to help the engine at all. I would just use an ordinary filter:
https://www.google.com/#q=rocker+breather...2289185d5cea093