road-warrior's list points out legitimate concerns. Exactly how any project should be handled.

I'm not one to step into an engineer's office and say "I want something for so and so". Like attorney's, most bill by the hour.
The right way, set the parameters for HIM to work within; not other way round, "This is what's needed, within this space...".
Then, so armed with road-warrior's questions and others, "Where are the impact guards,..." [etc].

One good thing; bulk of lateral stability is ledger at west wall, 18' high cinder block.
Right now, search is on for load bearing capacity of initially proposed floor joists of doubled purlin. Floor grating appears to be 195 lbs over 36" by 4'6" openings, where my material is only 2'4" wide.

Not unlike the roof replacement, nearly flat mopped asphalt. Met with all kinds of roofers who made a big show standing atop a 24' ladder. Peeking over te pediment, waving arms about, pitching what mounted to a maintenance contract [without cost controls on permits/ material/ labor], patch this hot mop that. On other side of ridge, one corner was collapsed.
One, he'd raise common rafters OVER existing roof, enclosing it. OMG
Not one even asked inside to adjudge condition of the 15 supporting posts. 6x6's in 3 rows -5 each- 6x6's, most termite eaten to half original size. 2 so far gone, they'd scabbed on 2x8 splints.

One didn't bring a ladder, asked inside FIRST. "We can't save this. The walls [brick] are sound. I'll cut old roof out, swing 65' trusses over, set on lumber plate 2"x12"s. It'll be 65' free span, plywood decking, 30lb paper, 50 year shingles and no posts at all. "65' BTW is longest [and highest at 4:12, ~10'9"] they can trailer through town."
Guess who got the job?
A few joke-roofers came by later. "I would have done this way also..." To each, the same response.

I'm a machinist. It's not my job to know roofing, even construction. You're used to homeowners, clients who have maybe no capabilities, just a sagging, leaky roof. You did nothing appraising entire situation, yet provided a quote. This is 50 year guarantee roof, for less than your 3.33 of re-dos. [15 yr warranties].