Times Cryptic Jumbo 1447

[NeilMunro]

Very grateful for all help with these clues please.
34ac: “Fake article providing cover under corporation, once (8).”
36ac: “Short testimonial that leads to another piece of work? (5-9).”
43ac: “Search two New England states united with Canadian region (7).”
58ac: “Way of working with general builder in goldmine (10).”

[Lie-in King]

34a Codpiece (worn under "corporation"; stomach) - 'cod (fake) piece (article)'
36a Cross-reference (short-testimonial)
43a Manhunt - 'Ma(ssachusetts) N(ew) H(ampshire) u(nited) N(orthwest) T(erritories)'
58a Moneymaker - 'mo' (way of working) + '(General) Ney' + 'maker'

[NeilMunro]

Many thanks Lie-in King!!!