Ask for details on what will be machined, and what parts will be replaced. You can machine the gas metering blocks to something usable, but ask if they enlarge the main well, modify idle fuel restriction, power valve channel restriction enlargement, etc. For optimization, you really should have the boosters changed, and the holes in the metering blocks feeding the boosters enlarged. IMO, the QF metering blocks are a good price because they are resized vs stock and are anodized to fight corrosion. If you machine the existing ones, you have bare aluminum exposed. The QF blocks also have screw in emulsion bleed holes (many to select) for tuning.

Does your carb already have screw in air bleeds? Because the air bleeds will need to be changed. Larger needle and seats too.