198 surges at partial throttle cruise

The kit from www.daytonaparts.com has a superior inlet needle/seat design and for that reason is worth getting. No kits (no matter the brand) come with the correct float gauge any more, all you get is a useless strip-of-paper ruler -- good reason to also pick up a NOS kit off eBay or wherever to grab hold of the float gauge. The float in your Holley 1920 carb is Nitrophyll (foam); they tend to take on fuel and grow heavy over the years. New float doesn't come in carb kit but is still available. While you're at it, wise to do the Fuel line mod.

It is not unusual that you can't move the EGR valve with mouth suction; most of us are not able to generate even close to the amount of vacuum needed to operate the stiffly-sprung EGR valve. If it doesn't move even when connected directly to manifold vacuum, or to a vacuum pump, that's another matter.

A blockoff plate looks nicer, but isn't necessary; you can leave the valve in place and it'll sit there doing nothing, or if you want to make super extra double sure you can remove the valve, flip it 180°, and reinstall it (with a new gasket).

Also make sure your thermostatic air cleaner system is intact and working correctly, and your manifold heat control valve isn't jammed and its spring isn't broken.

(Whoever pays $140+ for a carburetor rebuild it, no matter the model or size of carburetor, and no matter whether we're talking about American or Canadian dollars, needs to shop more carefully)