Are the front sight bases on Pre 64 type Model 94s soldered on?

On one of the two that I own the front sight base is quite crooked to the left. I can tell because on the other one its perfectly straight.

If its soldered on how much of a hassle is it to take it off and put it back on straight without ruining the bluing or the barrel?

Early ones are forged integral; later pre 64 ones are brazed on. Lot of hassle because brazing temp will ruin blue. I actually can't remember if they are brazed or soldered; if soldered then you can move it but you will have a line of silver showing. I've soldered lots of them on but never took one off.
How does it shoot?

high and to the left. Maybe I should look for a good used barrel for it.

I have several in 30-30 carbine..........
Or you can turn the barrel back to make the sights come out on top and widen the extractor cut. IF both sights are on the same plane. That is what I would do. If the barrel is not tight enough, upset the threads, or shoulder. Easy fix. If both sights are not in line, then, that is something else.

If it's shooting left, you would need to move the front sight even more to the left, so it would shoot worse if you resoldered it .. and 94's often have excessive headspace anyway (do your primers back out?) so unscrewing the barrel a tad will make that worse.

The early guns are now selling for a good sum so think carefully about doing anything to make it less "original" .. esp if it's an uncommon variant.