I'm not all that familiar with hardtail Strats but I imagine that it would be somewhat of an undertaking to convert a tremelo routed body to hardail. a tremelo gives you the added advantage of dropping (or raising also if it's 'floating")the pitch of a note and adding a pleasing subtle vibrato effect to your leads or rythym.As previously stated you don't need to change the nut or tuners,the originals will work fine especially if you put graphite or nut lube on all string contact points.Blocking the vibrato assembly is also an option if you decide that you don't like having the vibrato on it. Another thing to consider is that if you decide to sell it down the road you can sell a vibrato equipped Strat quicker and get more money than you would get for a hardtail as most people prefer having the vibrato.Over the years I've owned 5 Strats and all were vibrato equipped and I've never had tuning problems and furthermore the heavier standard vibrato tailpiece block can add greatly to sustain.

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'65 Strat,65 Mustang,65 Jaguar,4 more Strats,3 vintage Vox guitars,5 Vox amps,'69 Bassman with a '68 2-15 Bassman cab,36 guitars total-15asst'd amps total,2 vintage '60s Hammond organs & a myriad of effects-with a few rare vintage ones.