Let's use the average rate from mortgage news daily's website that I last saw at 6.5%

I think it's best to get this shock out of your system before you're further along.

Here's how it looks:

MortgageInterestTotal (principal + interest)
$800,000$1,020,356$1,820,356
$775,000$988,470$1,763,470
$750,000$956,584$1,706,584
$725,000$924,698$1,649,698
$700,000$892,811$1,592,811
$675,000$860,925$1,535,925
$650,000$829,039$1,479,039
$625,000$797,153$1,422,153
$600,000$765,267$1,365,267
$575,000$733,381$1,308,381
$550,000$701,495$1,251,495
$525,000$669,609$1,194,609
$500,000$637,722$1,137,722
$475,000$605,836$1,080,836
$450,000$573,950$1,023,950
$425,000$542,064$967,064
$400,000$510,178$910,178
$375,000$478,292$853,292
$350,000$446,406$796,406
$325,000$414,520$739,520
$300,000$382,633$682,633
$275,000$350,747$625,747
$250,000$318,861$568,861
$225,000$286,975$511,975
$200,000$255,089$455,089
$175,000$223,203$398,203
$150,000$191,317$341,317
$125,000$159,431$284,431
$100,000$127,544$227,544

That makes it 44%/56% for principal and interest.

Fun little fact: a 5% rate gets you at about 50/50