How to encode/decode correctly using NetSuite file upload in Suitelet

I'm trying to use NetSuite's N/file module to upload a file to DropBox. I've been successful at authentication, getting a 200 when submitting the POST request to Create FolderV2 and Upload File. However, I can't figure out how to get the file contents to set correctly. Currently, the file is being created with the some sort of encoding/decoding like this "UEsDBBQABgAIAAAAIQDfpNJsWgEAACAFAAATAAgCW0NvbnRlbnRfVHlwZXNdLnhtbCCiBAIooAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"

 

Here's the code:

/**
 *@NApiVersion 2.x
 *@NScriptType Suitelet
 *@NModuleScope Public
 */
define(['N/ui/serverWidget', 'N/file', 'N/https', 'N/encode'],
    function(serverWidget, file, https, encode) {
        function onRequest(context) {
            if (context.request.method === 'GET') {
                var form = serverWidget.createForm({
                    title: 'Upload Artwork',
                    hideNavBar: false
                });

                // Add File Upload
                var fileFld = form.addField({
                    id: 'custpage_file',
                    type: serverWidget.FieldType.FILE,
                    label: 'Upload File'
                });
                form.addSubmitButton({
                    label: 'Upload'
                });
                context.response.writePage(form);
            } else {
                // Getting File from NS File Field
                var fileObj = context.request.files['custpage_file'];
                // Setting Folder in File Cabinet
                fileObj.folder = 214960;
                var fileId = fileObj.save();
                // Getting/Logging File Contents
                var fileContents = fileId.getContents();
                log.debug({title: 'File Contents', details: fileContents});
                // File Contents = UEsDBBQABgAIAAAAIQDfpNJsWgEAACAFAAATAAgCW0NvbnRlbnRfVHlwZXNdLnhtbCCiBAIooAACAAAAAAAAAAAAAAAAA

                // Decode the String
                var decodedStr = toBase64(fileContents);
                log.debug({title: 'Decoded Contents', details: decodedStr});

                var headerObj = {};

                // Upload Request
                var res = https.request({
                    method: https.Method.POST,
                    url: 'https://content.dropboxapi.com/2/files/upload',
                    body: decodedStr,
                    headers: headerObj
                });

                // Write Response
                context.response.write(JSON.stringify(res));
            }
        }
        function toBase64(stringInput){
            return encode.convert({
                string: stringInput,
                inputEncoding: encode.Encoding.UTF_8,
                outputEncoding: encode.Encoding.BASE_64
            });
        }
        return {
            onRequest: onRequest
        };
    });