Background:
Long ago I had an unrealised fetish for Steinberger "cricket bat" headless guitars, which led me to discover the narrow-5 option whereby the 4-string neck & body was converted to accommodate 5 strings. Hence the narrow-5 (model XT2-5).

So:
Being a recent recipient by gift of an HB-4 kit, I began wondering if a narrow-5 conversion could be achieved. There appears to be enough room on the headstock to accommodate a 5th machine head; nut could be easily enough replaced; the floating bridge for arch top could be readily either replaced or modified to work for 5 strings. There may even need to be some additional bracing installed inside the hollow body for strengthening due to the extra string tension.

The main obstacle seems to be the string mount block for the tail piece. The standard tail piece supplied has 45mm span across the strings (15mm spacing). I envisage a replacement string mount block with a 48mm span (12mm string spacing) as the final puzzle piece to solve the HB-4-to-Narrow-5 conversion. Question is, how could such a replacement part be sourced?

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Peter