If we do not have a 911 address for a new construction, just a lot number and street name, is it acceptable to pull the flood determination on just the street name without a specific house number?

Your FHD vendor should be able to do the determination using the legal description for the property. A street can run for 10 miles - what good would that do you and how would they do it with just a street name?

From the forms instructions

2. COLLATERAL DESCRIPTION: Preparer should coordinate with user to ensure the collateral is sufficiently identified. Suggested forms of collateral identification include, but are not limited to, property address, parcel or lot number and longitude/latitude. If needed, additional information may be attached to this form.