I am trying to quickly search between a range of blocks which has a specific number of transactions, for example between blocks 350700 - 360000 which has 1234 transactions, thanks for the help
Blocks that contain an extact number of transaction in the mempool?
Take note that transactions that have included in blocks are no longer in the mempool.
In addition to LoyceV's service, you can go to blockchair.com and simply filter the blocks by transactions count.
Your example: https://blockchair.com/bitcoin/blocks?s=id(desc)&q=id(350700..360000),transaction_count(1234)