You are fitting a 429 big block into your 1971 mustang will the flywheel clutch and toploader from original 351 Cleveland fit up to 429?

No, the flywheel, clutch, and toploader from a 1971 Mustang 351 Cleveland will almost certainly not fit a 429 big block. While both are Ford engines and use a similar bellhousing bolt pattern, the 429 has a significantly larger diameter crankshaft and a different clutch disc diameter. The 351C's flywheel and pressure plate will simply be too small for the 429's clutch. Even if the bolt pattern *were* identical (which isn't guaranteed), the imbalance and different diameter would likely cause serious damage.

You'll need a flywheel, pressure plate, clutch disc, and possibly a different bellhousing specifically designed for the 429 engine and your Toploader transmission. Consult a parts catalog or a Mustang specialist to get the correct components. It's highly likely you'll need a 429-specific flywheel and clutch assembly. The bellhousing might be adaptable depending on which Toploader you have and the 429's specific year/configuration. A professional mechanic familiar with these swaps can best advise you on compatibility.