I would suggest a complete replacement or professional redo. I did my own on a 68' 300 that had three very small cracks and took me about 6 tries to get it right. Used products from Polyvance. Not discrediting them in any way but it takes some practice and knowledge of different materials and how they expand and contract at various rates. I live in a cold (-25 celicius in winter) climate 6 months and when I thought I had it perfected: when the sun hit it, up came the repair spots. Yours I think requires reforming/re-foaming which is why I suggest someone who has experience.