If I replace a neck it is no longer a conversion it then becomes a Custom Guitar, simply because the logo or brand name usually appears on the headstock. All major manufacturers are limited by production costs, model changes, etc. etc. The only way a large company can succeed is to offer compromised models that will fit into the budgets and needs of the largest segment of the population. The necks are carved thinner, all the frets are replaced and slab of Brazilian rosewood is installed on the neck. The bodies are solid 1 piece Koa and Korina wood.
Pickups are the customer's choice.
Tremolo is either a Paul Reed Smith, or a Wilkinson all the wiring and pots have been upgraded to the best available, tuners have been replaced with bright plated super accurate Schaller's all the hardware right down to the screws has been changed. The pickguard is a bright white pearloid. Fender's custom shop uses a less costly pearloid that has a yellowish tint. Of course whenever we build one of these we use parts that the customer specifies. Starting with a stock Gibson Les Paul, the neck joint is recarved, the top is replaced with a gorgeous bookmatched quilted or flame maple.