Delay blocks always allocate all the RAM when you drop them in. I'd start with the reverb and estimate how much RAM remains, then allocate that to the delay. After you drop the delay in, open the control panel and reduce the total delay time. To recalculate you need to either click on "Start Simulation" or make or break a connection. Changing control panel values does not automatically recalculate the algorithm.
The "Small Reverb" is probably the slimmest in terms of RAM requirements. There are a couple other reverb blocks where you can choose the number of delay lines. I'd set that to two and see what happens.
DL