You can always submit your measurement after placing the order. For now, just select Customize with Made to Measure, click Add to Shopping Bag and complete order. Later on go to Account section, visit My Orders page and submit your latest measurement.
If your bare chest size measurement is 40 inches, you should select size 40 only from the product page. The "Top Chest" attribute in the size chart refers to the garment's chest size. It is inclusive of the required 3 to 4 inches loosening, to ensure the right fit.
If your bare chest measurement falls between 2 sizes i.e 37 inches, you should select size 38.
https://www.utsavfashion.com/product/digital-printed-art-silk-kurta-set-in-peach-mly3001972509Digital Printed Art Silk Kurta Set in Peachhttps://medias.utsavfashion.com/media/catalog/product/cache/1/small_image/295x/040ec09b1e35df139433887a97daa66f/d/i/digital-printed-art-silk-kurta-set-in-peach-v1-mly300.jpg58.473USDInStock/men/men/plus/men/festive/men/art silk/men/pink/men/kurta pyjama/men/digital print/men/floral print/men/traditionalDigital Printed Art Silk Kurta Set in Peach <ul><li> Art Silk Kurta in Peach</li><li> This Readymade attire is Enhanced with Moulded Buttons, Digital, Floral Print and Resham Work and is Crafted in Chinese Collar Neck and Full Sleeve</li><li> Available with an Art Dupion Silk Churidar in Maroon</li><li> Do note: Footwear shown in the image is for presentation purposes only. Half to one inch may vary in measurement. (Slight variation in actual color vs. image is possible)</li></ul>USDtype_new:Kurta Pyjamacolorfam:Pinkfabric:Art SilkPinkArt SilkKurta Pyjama11%-20%MenReady to Ship, Within 2 days, Within 7 days, Within 10 days, Within 15 days, More than 15 DaysReadymadeFestiveMenswearDigital Print, Floral Print, Traditional34, 36, 38, 40, 4244, 46