How do I send this form's output to a new WordPress page?

It’s better to use Iframe in this case. Here is how I will do it. Do you really need the submit button? in this case I do it without submit button, you can change it to your needs. This example codes can be added to your WordPress page through Text Tab on editor

<style type="text/css">
    .hideframe {
        visibility:collapse;
        display:hidden;
        height:0px;
    }
</style>

<select id="car" name="car">
    <option value="none">None</option>
    <option value="calc">Borrowing Power Calculator</option>    
</select>

<script type="text/javascript">
    window.onload = function() {
        document.getElementById( 'car' ).onchange = function() {
            var calc = document.getElementById( 'calc' );
            if( this.value === 'calc' ) {
                calc.classList.remove( 'hideframe' );
            } else {
                calc.classList.add( 'hideframe' );
            }
        };
    }
</script>

<!-- iframe start -->

<div id="calc" class="hideframe">
    <iframe src="http://www.visionabacus.com/Finance/Australia/1/SuiteA100/640/Borrowing-Power-Calculator.aspx?ID=MFAA" />
</div>
<!-- iframe end -->