Rather than re-engineer the cart to use a different block? I mean, I guess when a part reaches end-of-life, your first move is to buy as many as you can, before you try to re-engineer things so it isn't needed, but... horsepower is horsepower. Torque is torque. It shouldn't be that hard to replace...
They did eventually replace the Buicks.
> The original design was conceived by two Lockheed Skunk Works engineers who had prior race car engine knowledge. In the mid-1970's, the engines of the start carts was changed to Chevrolet LS-7 454's. The Chevrolet big block engines developed 465 horsepower each. Even so, for many years they were still referred to as the Buick's.
https://www.thesr71blackbird.com/Aircraft/Engines/starting-t...
And eventually the start carts themselves got replaced.
> In the '80's the AG-330 Start Carts were mothballed and in there place came a Pneumatic Air starting system for the SR-71's. It is true that the start carts were hard to maneuver around. Logistically, a recovery of a Blackbird at another base could be done easier with Pneumatic Air.
Can the plane just carry....the starter ?, it's another 200-300kg of payload, may affect the max range, etc, but much more convenient.