I'm surprised you got any "real" info from Baker - most of the times I asked him a question in the past it was so non-committal it made me more confused than before I asked the question.
So - yes or no - Is my motorcycle helmet acceptable for a 19 second car?
From the rulebook
13.50 and slower 1/4 mile
9.00 and slower 1/8 mile
In addition to the following rules, also see IHRA E.T. Bracket Safety and General Rules.
Dragsters and Altereds prohibited in this section.
BODY: Must be full bodied car.
BRAKES: Four-wheel brakes mandatory.
DRIVELINE: Drive shaft loop mandatory on any vehicle using racing slicks. See General
Regulations
DRIVER: Must remain in stock location.
ENGINE: Automotive engine only. Must remain in OEM location.
EXHAUST SYSTEM: Headers permitted, must be designed to route exhaust gases away
from car. Flex pipe prohibited.
FIREWALL: OEM type mandatory.
FLOOR: Full floor mandatory.
FUEL SYSTEM: One stock location fuel tank maximum. Fuel cells recommended. Top of
fuel tank not to be higher than top of tires.
HELMET: SN 90 or newer mandatory on all entries running 13.99 (8.59 1/8th mile) or quicker. Entries running 14.00 (8.60 1/8th mile) & slower, helmet is recommended.
HOOD: Mandatory.
MASTER CUTOFF: See General Regulations.
ROLL BAR: Recommended. See General Regulations.
STEERING: Steering box location optional. Steering must be located in conventional
location on driver’s side of car.
TRANSMISSION: Any OEM type transmission permitted. Neutral safety switch required.
WHEELBASE: Minimum: 90” unless car has original engine and OEM is shorter.
Wheelbase variation left to right: 1” maximum.
WHEELS &TIRES: Must be automotive-type wheels suitable for street use. Racing slicks
permitted. Automotive wire wheels or motorcycle wheels prohibited. Minimum wheel size
is 13” unless originally equipped with smaller wheels and is using the original engine.
Recap tires prohibited.
Note
HELMET: SN 90 or newer mandatory on all entries running 13.99 (8.59 1/8th mile) or quicker. Entries running 14.00 (8.60 1/8th mile) & slower, helmet is recommended.
Looks like 14.00 and under you do not need a helmet, put on whatever helmet you have and it will be more than is required.