There is zero point in melding beyond 340 Gathering total (which will hit the 90% gathering cap on unspoiled nodes, and 95% cap on clusters), 600GP total (since 650GP can't be reached practically and only offers minimal benefit to do so anyway), and for Perception, once you've passed the basic 320 value, just throw whatever trash perception material you have into any spare slots and don't worry about over-melding and burning tons of gil. My advice, aim for 335 Perception and stop worrying about it from there. Get 350 perception only if it's easily achievable with the material you have in stock, but don't go burning 1M gil to get it.