Reinier, this is only a two-stop B&W push, so you should be able to save the images, even though you will lose shadow detail. To process T-Max 100 at 400, Kodak recommends 12 minutes at 68 degrees in T-MAX developer, or 9 minutes at 75 degrees. Anchell and Troop give 11 minutes at 68 degrees in D-76 or ID-11; 9 minutes in full-strength XTOL; 12.5 minutes in XTOL 1:1; 9.5 minutes in HC110 dilution B.(posted 8288 days ago)The extra development will increase the contrast, so you may need to print softer.
Best Wishes,