Plenty of 34” scale 5 strings out there (‘Ray5 for example) so a 34”, 4 string, tuned BEAD, shouldn’t be an issue. Avoiding smaller tuner capstans will remove any need for alterations there (Fender/MM/etc type). However, widening of the fret slots will probably be required, as all 4 slots will be taking a thicker string than intended, unless you go for a gauge that is light enough to negate this small modification.