MS70 PCGS only

i have been collecting $5 gold american eagles for several years now and all the coins are PCGS graded. my set ranks 8th in the NGC registry and 4th in the PCGS registry. the coins were minted from 1986 to date. the only coins i need in MS70 to have a complete set of PCGS MS70 graded coins are 1988 to 1993. these are very low pop. coins from 1 to 5 [PCGS]. i have not been able to locate any except those graded by NGC. the NGC pops are much higher than the PCGS pops for MS70. i have been considering buying NGC graded coins and cracking them out of the case and submitting them to PCGS for grading. i have tried this on 2-2001 NGC MS70 coins and PCGS graded them MS69. now the coins i need are $500+ each and they could end up being a very expensive MS69 PCGS coin. i don't dare submit the coins in the NGC slab as that is a guarantee PCGS will give you a 69 grade. this is quite a problem. has anyone have any advice as to what to do.