45 basis points isn't a spread, it's rounding error. Merchant builders in industrial have generally wanted 150 to 200 basis points of yield on cost over the cap they expect at exit, and the reason isn't greed. It's that the exit cap is the single input you have the least control over and it's being estimated two and a half years forward.
Do the sensitivity. At 5.75 you're worth $12.17M against $11.2M of cost, so about $970k of value creation, an 8.7 percent margin on cost. Push the exit to 6.5, which is well inside the range caps have moved in a normal 24 month stretch, and you're worth $10.77M. The project is underwater and you've personally guaranteed completion. That asymmetry is the whole answer to your question.
The $145 hard cost needs interrogation too. Confirm what structural system it assumes and what clear height. Tenants asking $12.50 on shallow bay usually want 28 to 32 foot clear now, and if your number was built off a 24 foot building you're short. Steel-intensive scopes have carried real embedded tariff cost per square foot, and the only way to hold that line is buying out steel early, ideally at GMP with the joist and deck package locked before you close the loan.
Two things your model probably doesn't have. One is the interest reserve sized for a lease-up period, not just construction. Spec shallow bay can sit six to twelve months after CO, and someone funds the carry. The other is TI and leasing commissions on a spec building, which for multi-tenant shallow bay is not zero, and if you're splitting 60,000 feet into four bays you're paying for demising walls, extra dock positions, and separate offices that a single-tenant pro forma never included.