I think it would be hard for any of us to recommend what RPM level your engine will run at. That is something your builder or someone who runs a 421 can tell you. You have all the good parts, so you may be on the conservative/safe side. I am building my 455CI looking to spin 5,800 RPM, but it will be the cam/heads that dictate where the power drops off because the shortblock will certainly spin more.
I think your limits look OK to me as long as all clearances are right and your oil pump is up to the job. I would not be pushing the limits quite yet until you have gotten some miles on the engine and dialed in all your components, especially your distributor. If not done right, you can get detonation that you cannot hear and you may find yourself wiping out another set of bearings. I think I would go conservative and set my RPM limit at 5,200 RPM's until I got some mileage on the engine to seat everything and got my ignition dialed in.
10 to 1 compression is still a bit high for the "77" closed chamber iron heads for a street cruiser. You will most likely need a good 100 octane racing gas or true octane booster. The pump 93 octane may not cut it. Many topics found here on the forums under "pinging", "compression", "timing" etc. that should help you out.
Its your call, but personally, I would not be taking a car on a long trip (?) just out of the engine builder without sorting the engine out on the road locally first. But...... I have done it myself.