The key question is would the USSR still deliver weapons to a more powerful UAR? In 1961 France was still the main weapon supplier of Israel and the involvement of the USA was low. So the reaction of Russia had the key to success for the UAR. Because without arms they would have a problem.
Could we see that both as a need for a more powerful Arab state and one that isn't dominated by any single power? Because Nassar doesn't seem the type to take a hint.
As for the USSR…*I don't know. It would be very interesting if the UAR turns to European arms/support as a way to partially escape the USSR/USA divide. Could the UAR convince more states to join? Jordan in particular would be a major grab, and could see the region shifting to a neutral Cold War stance.
I believe the USSR was pretty much entrenched as the arms supplier to Egypt, Syria, and Iraq. What those countries provided the Soviets with was a solid source of hard currency in exchange for their weapons, and a good chance that the weapons would be used (information on their usefulness was always good).
The Warsaw Pact countries never could provide the USSR with that much cash. Who's got more money coming in from exports, Egypt from the Suez Canal, or Hungary from...being a Soviet puppet? It was that sort of thing.
This didn't mean that the Egyptians weren't interested in becoming independent. They were co-developing a light fighter with the Indians and Yugoslavians.
I'll have to find the article I've got on it. There's an interview that Military History did with the test pilot. They destroyed one of the prototypes on the ground, but they ended up coming out of it with a good jet engine that the Indians ended up developing into the Kaveri that they're using currently in their LCA.
I believe the Soviets would've looked on a UAR as something that might just be a better business partner. Obviously, they'd want to sell the UAR as much as they could, but the Israelis were cutting it real close during the '67 and '73 wars.
What the USSR might want to sell them was more naval forces, even though the Egyptians might not be interested in buying them after what happened to the Israeli destroyer
Eilat in '67, sunk by Styx anti-ship missiles.
If the UAR could be convinced it wanted a naval force, it would increase it's dependency on the USSR for spare parts, weapons, radars, etc. It would in effect create a Soviet client state surface action group OUTSIDE the Bosporus.
If the Soviet Union strikes a deal that says something to the effect of "We give you cheap stuff if you give us cheap facilities," then that's a big problem for the US 7th Fleet in the Med.
Or, of course, they could go the route the Egyptians were going, and try going the middle route with India and Yugoslavia, trying to develop and field weapons systems that are basically heavily modded home-built copies of Soviet and Western systems.