Adjusting thrustline of rubber powered models

Following refers to those with removable balsa nose piece.

1. 2 brass/copper bushings glued to the front and rear of the nose piece, and a glass bead. (Herr Engineering's Piper Tri-Pacer)
2. 1 aluminium tubing glued through the nose piece. Use cup/flat washers or glass bead.
3. 2 small aluminium (from drink can) flat pieces, pierced in centre to pass through the motor shaft, with tabs to bite into nose piece. Glass bead or cup washer for bearing. 

Method 1 and 2 can only be made adjustable by shimming the whole nose block. When a hole is drilled and the bushing or tubing glued in, the angles of side and down thrust is fixed, relative to the nose block, so the nose block has to be shimmed to adjust the angles. It does leave a gap all round the nose block but maybe some paper glued on the nose piece will cover it up. It's not too bad then. Don't you think that having the propeller and the nose piece 'square' with each other looks nicer?

 Method 3 can allow thrustline adjustment if the balsa nose piece is drilled larger or slotted. We only need to prise off the rear piece and reposition. The pulling force is on the front piece, the rear piece only guides the motor shaft and withstand the side force. For neatness, the front piece need not have anchoring tabs, it may be glued to nose piece. Alternatively, front piece can also be made from plywood or other harder wood pieces so long as the glass bead won't pull through. As nose weight is usually needed anyway, can consider using thicker and heavier pieces. A spiked nut may be good for the front piece, the smallest available spiked nut is may be 3mm, but so long as the glass bead don't get pulled through, it can be used.  Maybe 2 spherical glass beads are better to reduce friction due to compression forces. The drawback? Maybe the look of the propeller hung skewed to the nose block.