20-fret neck replacement for a 21-fret Ibanez rb650

Ibanez rb650 - 1984 - Made in Japan

The original Ibanez neck is a 34-inch scale, 21 frets maple neck - Full body, no over hang.

It is to bent and I cannot repair it.

I am looking for Chinese replacement necks from 60-100 Euros. There are 21 fret versions, but not as many as the standard 20-fret version.

Now my question is, can I put a 20-fret neck on the body of the - Ibanez rb650.
The 20-fret replacement necks have the same length like the original Ibanez?

From nut to the "real" end of the neck it's 24.4 inches.
Will I have to adjust the bridge position, or can I just move the saddles forward or backwards, because of the intonation?

Sorry for the bad english.

 

Anyone

Ok thanks, great advice!